.
`
`UIllted States Patent [19]
`Cage
`
`USOO5373745A
`
`[11] Patent Number:
`[45] Date of Patent:
`
`5,373,745
`Dec. 20, 1994
`
`[54] SINGLE PATH RADIAI MODE CORIOLIS
`MASS FLOW RATE METER
`
`[75] Inventor: Donald R- Cage, Longmont, C010-
`.
`.
`.
`[73] Ass‘gmw D‘mt Measmment Cwmmtwn,
`LongmOnt, (3010-
`_: 16 19
`21 A 1_
`[
`1
`Pp No
`7’7
`[22] Filed:
`Dec. 15, 1993
`
`4,798,091 1/1989 Lew .................................... .. 861/73
`4,811,606 3/1989 Hasegawa et a1.
`861/73
`4,823,614 4/1989 Dahhn .............. ..
`861/73
`4,831,885 5/1989 Dahlin .......... ..
`861/73
`4,852,410 8/1989 Corwo et al.
`861/73
`4,856,346 8/1989 Kane ............. ..
`.. 861/73
`4,891,991 1/1990 Mattar et al .... ..
`.. 861/73
`4,934,195_ 6/1990 Hussain ............................... .. 861/73
`4,949,583 8/1990 Lang et al
`5,024,104 6/1991 Dames
`
`Related U 5 Application Data
`
`FOREIGN PATENT DOCUMENTS
`
`[63]
`
`Continuation of S61‘. NO. 843,519, May 8, 1992, aban-
`doned and S61’ NO 651301 Feb 5 1991 abandoned
`’
`'
`‘
`’
`’
`‘
`’
`’
`‘
`[51] Int. Cl.5 .............................................. .. G01F 1/78
`[52] Us. Cl. _____________________________ __ 73/861_37;73/861_18
`[58] Field of Search .......... .. 73/861317, 861.38, 861.18
`[56]
`Referelces Cited
`U s PATENT DOCUMENTS
`'
`'
`Re. 31,450 11/1983 Smith .................................. .. 861/73
`3,927,565 12/1975 Pavlin .... ..
`73/861.38
`
`gm“ '
`8885223642
`“many '
`'
`0272758 12/1987 Italy .
`62480741 7/ 1937 Japan -
`1008617 3/1933 U.S.S.R. ......................... .. 73/86L37
`Primal), Examiner__walter E. snow
`Assistant Examiner-Raymond Y. Mah
`Attorney, Agent, or Firm—K0nneker Bush Hitt &
`Chwang
`
`[57]
`
`ABSTRACT
`
`4,109,524 8/ 1978 Smith . . . . . .
`
`. . . . . . . . . .. 194/73
`
`'
`
`-
`
`4,420,983 12/1983 Langdon . . . . .
`4,422,338 12/1983 Smith . . . . . . . _ . .
`4,491,025 1/1985 Smith et al
`4,622,858 11/1986 Mizerak .... ..
`
`. . . . .. 73/861.18
`. . . . . .. 861/73
`361/73
`861/73
`
`A ?ow mete,‘ aPPa’amS for n_‘ea_s“m_g Fhe mass _?°w
`fat? of a mud usufgfhe C°n°11s P9119118?- A 51113316
`straight ?ow conduit 18 employed WhlCh 1s vibrated in a
`radial-mode of vibration. Coriolis forces are thereby
`
`
`
`4,628,744 12/1986 ;/
`
`
`
`. . . . . . . . . . . . gnome“
`
`. . . . . .. 861/73
`
`
`
`produced along the walls of the ?ow conduit deform the conduit’s cross-sectional shape as a function
`
`mouse“ ct
`/
`’
`’
`4,691,578 9/1987 Herzl ............ ..
`4,716,771 V1988 Kane _____________ __
`4,728,243 3/1988 Friedland et a1
`4,733,569 3/1988 Kelsey .......... ..
`4,756,197 7/1988 HC1'21 . . . . . . .
`
`861/73
`
`861/73
`_____ __ 351/73
`73/861.38
`. . . . . ..
`73
`
`4:776:220 10/1988 LEW ........... ..'..:
`4,793,191 12/1988 Flecken et a1.
`
`IIIII " 861/73
`861/73
`
`of mass flow rate. Additional embodiments are dis
`.
`.
`.
`.
`closed employing vibranon of selected pornonsof the
`?ow condmt walls. In addiuon, a method 18 descnbed to
`determine the pressure and the density of a ?uid by
`Simultaneously vibrating a ?ow conduit in two modes
`
`of vibration and thereby determining pressure and den
`my based on changes 1“ each frequency‘
`38 Claims, 27 Drawing Sheets
`
`1
`
`1
`
`Micro Motion 1003
`
`

`
`US. Patent
`U.S. Patent
`
`Dec. 20, 1994
`Dec. 20, 1994
`
`Sheet 1 0f 27
`Sheet 1 of 27
`
`5,373,745
`5,373,745
`
`FIG. 1
`FIG.
`1
`
`2
`
`2
`
`

`
`US. Patent
`U.S. Patent
`
`Dec. 20, 1994
`Dec. 20, 1994
`
`Sheet 2 of 27
`Sheet 2 of 27
`
`5,373,745
`5,373,745
`
`
`
`/ ///./7/ ///./7/
`
`44
`
`fig“gs.gig‘Ea
`
`v\
`
`
`
`// /// l/l
`
`%
`
`.u: <
`k
`
`3K..
`
`2m<N.w
`
`&§
`
`m OE
`
`3
`
`3
`
`

`
`U.S. Patent
`
`Dec. 20, 1994
`
`Sheet 3 of 27
`
`5,373,745
`
`K
`
`
`
`".......'..‘...'..'..I...:...':....D..V .A%2%‘$”.m_"._..any“war
`‘EIE1’;2",‘Vi;‘
`
`an
`
`mm
`
`
`
`i““'.:“ll“‘.‘.".’,"."‘a"‘.'.."..4I
`
`Hw§KmUE“I..
`
`L
`
`4
`
`4
`
`
`

`
`US. Patent
`
`Dec. 20, 1994
`
`Sheet 4 of 27
`
`5,373,745
`
`
`
`IIII' JlL
`
`FIG 4
`
`5
`
`5
`
`

`
`US. Patent
`
`Dec. 20, 1994
`
`Sheet 5 of 27
`
`5,373,745
`
`FIG 5
`
`FIG 6
`
`FIG '7
`
`6
`
`6
`
`

`
`US. Patent
`
`Dec. 20, 1994
`
`Sheet 6 of 27
`
`5,373,745
`
`FORCE
`
`CORIOLIS FORCE DISTRIBUTION
`ALONG TOP SURFACE OF CONDUIT
`
`DISTANCE ALONG FLOW CONDUIT ————D
`
`‘___
`
`' Aiiiiiiiiiiiihhn--
`
`A
`
`CORIOLIS FORCE DISTRIBUTION
`ALONG BOTTOM SURFACE OF CONDUIT
`
`FIG 8
`
`v
`
`\\\\\\ \
`
`7
`
`7
`
`

`
`US. Patent
`U.S. Patent
`
`Dec. 20, 1994
`Dec. 20, 1994
`
`Sheet 7 of 27
`Sheet 7 of 27
`
`5,373,745
`5,373,745
`
`G I F
`
`C 9
`
`8
`
`8
`
`

`
`US. Patent
`
`Dec. 20, 1991
`
`Sheet 8 of 27
`
`5,373,745
`
`FIG 10
`
`FIG 12
`
`FIG 13
`
`9
`
`9
`
`

`
`US. Patent
`
`Dec. 20, 1994
`
`Sheet 9 of 27
`
`5,373,745
`
`16 ¥'—\\\
`
`\
`
`\\
`\\
`\\
`
`15
`
`I"
`
`I
`
`I,’
`/
`
`SIGNALS IN PHASE
`WITH NO FLOW RATE
`
`\\
`‘\
`\\
`\\\
`
`,1
`I/
`1/
`/"
`
`FIG 14
`
`__ .__ SIGNALS SHIF'I‘
`WITH FLOW RATE
`
`FIG 15
`
`10
`
`10
`
`

`
`US. Patent
`
`Dec. 20, 1994
`
`Sheet 10 of 27
`
`5,373,745
`
`13
`/'
`mm;l /
`
`15
`
`v
`
`
`
`14 /‘
`awn’:
`
`1s
`
`7.8
`
`19
`
`18
`
`FIG 16
`
`11
`
`11
`
`

`
`US. Patent
`
`Dec. 20, 1991
`
`Sheet 11 of 27
`
`5,373,745
`
`28 / / 21B
`
`21A
`
`20
`
`21C
`
`FIG 18
`
`25
`
`22.
`
`21
`
`24
`
`23
`
`l?l
`
`12
`
`12
`
`

`
`US. Patent
`
`Dec. 20, 1994
`
`Sheet 12 of 27
`
`5,373,745
`
`DRIVE FREQUENCY
`RESPONSE FREQUENCY
`
`TOP SURFACE
`FORCE PROFILE
`
`mm
`
`BOTTON SURFACE
`FORCE PROFILE
`
`‘A
`
`I
`
`FIG 21
`
`13
`
`13
`
`

`
`US. Patent
`
`Dec. 20, 1994
`
`Sheet 13 of 27
`
`5,373,745
`
`FIG 23B
`
`14
`
`14
`
`

`
`US. Patent
`
`Dec. 20, 1994
`
`Sheet 14 of 27
`
`5,373,745
`
`26
`
`/ ////1
`
`J11 I
`
`///
`
`\\\\\\\\\\\\\\\\\\
`\
`
`FIG 24
`
`15
`
`15
`
`

`
`US. Patent
`U.S. Patent
`
`Dec. 20, 1994
`Dec. 20, 1994
`
`Sheet 15 of 27
`Sheet 15 of 27
`
`5,373,745
`5,373,745
`
` \\‘M.\.coo
`
`I/I
`
`103
`103
`
`108
`8O1.
`
`101
`101
`
`123
`123
`
`125
`125
`
`124
`124
`
`117
`117
`
`119
`119
`
`118
`118
`
`111
`111
`
`113
`113
`
`112
`112
`
`160
`180
`
`161
`161
`
`'109
`
`102
`
`..//...‘AI_.\\\sS
`.Imm...u§.
`
`
`
`
`
`
`
`/I
`
`
`
`
`
`
`
`
`
`B77222.ntltlaZ///////////.r///.r//////////,7///1%//.r//////////////4.///////////t.,/////..722rl
`
`106
`01.
`
`110
`
`126
`
`128
`
`127
`
`120
`
`122
`
`121
`
`114
`
`X
`
`116
`
`115
`
`Y
`
`04.O%%72%11m51N5.11.1..21.21.11.O61.1.1.1.1.1.
`
`‘92
`G9YM7Hm
`
`104
`
`107
`
`105
`FIG. 25
`5
`
`129
`
`I.IlflIx......\\\\\\\\\\‘~.\\\In.\\\\/1:45.17fizz////Am
`
`16
`
`16
`
`
`
`
`

`
`US. Patent
`
`Dec. 20, 1994
`
`Sheet 16 of 27
`
`5,373,745
`
`112
`
`131
`
`mss now RATE
`‘————l>
`140
`PRESSURED
`\\
`“WP-‘-
`DENSITY D
`____{>.
`134 '
`PROCESSOR TEMP
`
`:'
`:
`
`01
`
`=
`(1
`‘
`115
`
`v 141
`
`13o
`I146
`TEMP
`
`\
`
`1s5\
`
`_...r\__r
`
`1
`
`VISCOSITY
`USER
`‘———{DEmD >
`
`a:
`
`E E
`I! O
`D IL
`
`165
`
`166
`
`(
`109
`132
`124 /
`M '\ A
`Q:
`% k ’
`
`M
`
`144
`\F.
`PRIMARY
`
`DRIVE
`
`"
`
`127
`
`(I 18
`E
`
`:
`
`a
`
`133
`
`164
`
`145
`
`(
`Mré
`v \ SEC‘ONDARY
`DRIVE
`1% (
`i
`143
`
`137
`
`f 5
`\ 139
`
`\- 13s
`
`FIG. 26
`
`17
`
`17
`
`

`
`US. Patent
`
`Dec. 20, 1994
`
`Sheet 17 of 27
`
`5,373,745
`
`SHIFT WI
`
`FLOW ""—‘> ‘I’
`
`135
`
`18
`
`18
`
`

`
`
`
`U.S. PatentU.S. Patent
`
`
`
`Dec. 20, 1994Dec. 20, 1994
`
`
`
`Sheet 18 of 27Sheet 18 of 27
`
`
`
`5,373,7455,373,745
`
`19
`
`19
`
`

`
`U.S. Patent
`
`Dec. 20, 1994
`
`Sheet 19 of 27
`
`5,373,745
`
`FIG. 31
`
`101
`
`FIG. 32
`
`FIG. 33
`
`20
`
`20
`
`20
`
`

`
`U.S. Patent
`
`Dec. 20, 1994
`
`Sheet 20 of 27
`
`5,373,745
`
`151
`
`151
`
`151
`
`153
`
`FIG. 34
`
`152
`
`153
`
`FIG. 35
`
`152
`
`153
`
`FIG. 36
`
`152
`
`21
`
`21
`
`

`
`
`
`U.S. PatentU.S. Patent
`
`
`
`Dec. 20, 1994Dec. 20, 1994
`
`
`
`Sheet 21 of 27Sheet 21 of 27
`
`
`
`5,373,7455,373,745
`
`
`
` 751. 751.
`
`
`
`158158
`
`
`
`157157
`
`
`
`158158
`
`
`
`157157
`
`
`
`158158
`
`22
`
`22
`
`

`
`U.S. Patent
`
`Dec. 20, 1994’
`
`Sheet 22 of 27
`
`5,373,745
`
`1'72
`
`108
`
`101
`
`123
`
`125
`
`124
`
`117
`
`119
`
`118
`
`111
`
`
`
`\¢m. . E.I..-._..I.“L4."r...Twv'..."...u.‘.w.I....._..I.....a...""‘.l.'7!
`
`
`
`
`99'4","EdaV"."‘.»"!W"‘4i".."’l§
`_....|IlIIlIlII'
`
`
`
`
`n.___.
`
`163
`
`011.
`
`126
`
`128
`
`127
`
`120
`
`122
`
`121
`
`114
`
`116
`
`115
`
`104
`
`107
`
`J
`
`FIG. 40
`
`162
`
`129
`
`.6.
`
`
`
`._:...l"A_.P...-1
`
`“E:
`
`..:
`
`'£"".,""‘.7"”‘fl'Ir""i!a"‘Eiél
`
`
`
`
`
`
`7‘AIn"“V‘lfiu:n.'.:3.5.:._..I.''‘l...u..u.....'..:...hi‘.~\‘~;NV‘L
`l‘I!Il‘IlI,o2
`
`El
`fi_+§‘\
`
`5I
`
`23
`
`23
`
`23
`
`
`
`
`
`

`
`U.S. Patent
`
`Dec. 20, 1994
`
`Sheet 23 of 27
`
`5,373,745
`
`103
`
`108
`
`117
`
`111
`
`160
`
`m1M
`
`«
`
`'1II.V/41’
`
`\I’;l'.‘u1'.‘'.’A..‘.unI.I.IlIIFI.l1'l|.I.l_'I.r‘....IIIIL
`
`
`"!r“¢a“7’.".‘A"""ln’E"V_
`
`u_
`:_
`
`_vI.lfl..
`
`L\
`
`AIIIIIIII.
`
`ii.V.~k‘!Il.I|IIII.lIv.'l....._|ullIl!lV“l.I.III.ll:I""“4I.'
`
`47’Mmmu
`
`éalua
`
`mu.
`
`106
`
`110
`
`126
`
`120
`
`104
`
`114
`
`Y
`
`107
`
`FIG. 4 1
`
`129
`
`24
`
`24
`
`
`

`
`U.S. Patent
`
`Dec. 20, 1994
`
`Sheet 24 of 27
`
`5,373,745
`
`202
`
`202
`
`203
`
`200
`
`202
`
`FIG. 44
`
`2O1
`
`203
`
`gm
`
`25
`
`25
`
`25
`
`

`
`
`
`U.S. PatentU.S. Patent
`
`
`
`Dec. 20, 1991Dec. 20, 1991
`
`
`
`Sheet 25 of 27Sheet 25 of 27
`
`
`
`5,373,7455,373,745
`
`
`
`
`
`
`
`168168
`
`
`
`167167
`
`
`
`108108
`
`
`
`106106
`
`
`
`
`
`L_.XL_.X
`
`
`
` LE.-.-I>:::::::::::II LE.-.-I>:::::::::::II
`
`
`
`7A <57A <5
`
`
`
`
`
`
`
`4646
`
`
`
`101101
`
`
`
`FIG. 47FIG. 47
`
`
`
`2626
`
`26
`
`26
`
`

`
`U.S. Patent
`
`Dec. 20, 1994
`
`Sheet 26 of 27
`
`5,373,745
`
`t;
`
`g M,
`
`
`
`Secondary
`
`FIG. 50
`
`170
`
`PRESSURE
`
`FIG. 51
`
`
`
`23
`
`E E
`
`’
`
`DENSITY
`
`FIG. 52
`
`TEIPERATURE
`
`27
`
`27
`
`27
`
`

`
`
`
`U.S. PatentU.S. Patent
`
`
`
`Dec. 20, 1994Dec. 20, 1994
`
`
`
`Sheet 27 of 27Sheet 27 of 27
`
`
`
`5,373,7455,373,745
`
`
` 173 //////////// 177 173 //////////// 177
`
` 173 173
`
` 173 173
`
`28
`
`28
`
`

`
`1
`
`5,373,745
`
`2
`number of problems which preclude the use of Coriolis
`technology in many applications that would benefit
`from its use.
`Among the problems caused by the flow splitters and
`curved flow conduits are: (1) excessive fluid pressure-
`drop caused by turbulence and drag forces as the fluid
`passes through the flow splitters and curves of the de-
`vice, (2) difficulty in lining or plating the inner surface
`of geometries having flow splitters and curved flow
`conduits, with corrosive resistant materials, (3) inability
`to meet food and pharmaceutical industry sanitary re-
`quirements such as polished surface finish, non-pluga-
`ble, self-draining, and visually inspectable, (4) difficulty
`in designing a case to surround dual curved flow con-
`duits which can contain high rated pressures, (5) diffi-
`culty in designing flow meters for 6" diameter and
`larger pipelines and (6) difficulty in reducing the cost of
`current designs due to the added value of flow splitters,
`dual flow conduits and curved flow conduit fabrication.
`
`It is therefore recognized that a Coriolis mass flow
`rate meter employing a single straight flow conduit
`would be a tremendous advancement in the art. It is the
`
`object of the present invention therefore to disclose a
`means whereby a Coriolis mass flow rate meter can be
`created using a single straight flow conduit thereby
`eliminating the problems caused by flow splitters, dual
`flow paths and curved conduits while retaining the
`current advantages of balance and symmetry.
`SUMMARY OF THE INVENTION
`
`The foregoing has outlined rather broadly the fea-
`tures and technical advantages of the present invention
`in order that the detailed description of the invention
`that follows may be better understood. Additional fea-
`tures and advantages of the invention will be described
`hereinafter which form the subject of the claims of the ,
`invention. It should be appreciated by those skilled in
`the art that the conception and the specific embodiment
`disclosed may be readily utilized as a basis for modify-
`ing or designing other structures for carrying out the
`same purposes of the present invention. It should also be
`realized by those skilled in the art that such equivalent
`constructions do not depart from the spirit and scope of
`the invention as set forth in the appended claims.
`According to the object of the present invention, a
`Coriolis mass flow rate meter is herein provided utiliz-
`ing a single straight flow conduit and a unique vibration
`method thereby eliminating the problems caused by
`flow splitters and curved flow conduits while retaining
`the current advantages of balance and symmetry.
`The basic operation of a commercially available Cori-
`olis mass flow rate meter according to current art will
`now be described. Normally two process-fluid filled
`flow conduits are employed in a parallel-path or serial-
`' path configuration. The two flow conduits form a bal-
`anced resonant system and as such are forced to vibrate
`in a prescribed oscillatory bending-mode of vibration. If
`the process-fluid is flowing, the combination of fluid
`motion and conduit vibration causes Coriolis forces
`which deflect the conduits away from their normal (no
`flow) paths of vibration proportionally related to mass
`flow rate. These deflections, or their effects, are then
`measured as an accurate indication of mass flow rate.
`As previously described, only one flow conduit is
`necessary for measuring mass flow rate in this manner.
`However, to achieve the superior performance afforded
`by a balanced resonant system, it’s necessary to counter-
`
`SINGLE PATH RADIAL MODE CORIOLIS MASS
`FLOW RATE METER
`
`RELATED APPLICATION
`
`This is a continuation of application Ser. No.
`07/843,5 19, abandoned filed May 8, 1992 and Ser. No.
`07/651,301, filed Feb. 5, 1991 now abandoned.
`
`TECHNICAL FIELD OF THE INVENTION
`
`10
`
`This invention relates to Coriolis mass flow rate me-
`ters and, in particular, to Coriolis mass flow rate meters
`using a single straight flow conduit to measure mass
`flow rate.
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`BACKGROUND OF THE INVENTION
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`In the art of Coriolis mass flow rate meters it is well
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`known that a vibrating flow conduit carrying mass flow
`causes Coriolis forces which deflect the flow conduit
`away from its normal vibration path proportionally
`related to mass flow rate. These deflections or their
`effects can then be measured as an accurate indication
`of mass flow rate.
`This effect was first made commercially successful by
`Micro Motion Inc. of Boulder Colo. Early designs em-
`ployed a single vibrating U-shaped flow conduit which
`was cantilever mounted from a base. With nothing to
`counter-balance the vibration of the flow conduit, the
`design was highly sensitive to mounting conditions and
`so was redesigned to employ another mounted vibrating
`arrangement which acted as a counter-balance for the
`flow conduit similar to that disclosed in their U.S. Pat.
`Nos. Re. 31,450 and 4,422,338 to Smith. Problems oc-
`curred however since changes in the specific gravity of
`the process-fluid were not matched by changes on the
`counter-balance, an unbalanced condition could result
`causing errors. Significant improvement was later made
`by replacing the counter-balance arrangement by an-
`other U-shaped flow conduit identical to_ the first and
`splitting the flow into parallel paths, flowing through
`both conduits simultaneously. This parallel path Corio-
`lis mass flow rate meter (U.S. Pat. No. 4,491,025 to
`Smith et al.) solves this balance problem and has thus
`become the premier method of mass flow measurement
`in industry today.
`Many other flow conduit geometries have been in-
`vented which offer various performance enhancements
`or alternatives. Examples of different flow conduit ge-
`ometries are the dual S-tubes of U.S. Pat. Nos. 4,798,091
`and 4,776,220 to Lew, the omega shaped tubes of U.S.
`Pat. No. 4,852,410 to Corwon et al., the B-shapes tubes
`of U.S. Pat. No. 4,891,991 to Mattar et al., the helically
`wound flow conduits of U.S. Pat. No. 4,756,198 to
`Levien, figure-8 shaped flow conduits of U.S. Pat. No.
`4,716,771 to Kane, the dual straight tubes of U.S. Pat.
`No. 4,680,974 to Simonsen et al. and others. All of these
`geometries employ the basic concept of two parallel
`flow conduits vibrating in opposition to one another to
`create a balanced resonant vibrating system.
`Although the parallel path Coriolis mass_flow rate
`meter has been a tremendous commercial success, sev-
`eral problems remain. Most of these problems are a
`consequence of using flow splitters and two parallel
`flow conduits in order to maintain a balanced resonant
`system. In addition, most designs employ flow conduits
`that are curved into various shapes as previously de-
`scribed to enhance the sensitivity of the device to mass
`flow rate. These two common design features cause a
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`balance the reaction forces from the forced vibration,
`thus a second flow conduit is normally employed. For
`very small meter designs the mass and stiffness proper-
`ties of the mounting conditions can be sufficiently great
`to counteract the reaction forces from the forced vibra-
`tion thereby allowing the use of only one flow conduit.
`Accordingly, Micro Motion Inc. presently offers only
`their two smallest flow meters, the model D6 (1/16"
`line size) and the model D12 (§” line size) in a single
`curved flow conduit configuration.
`A single straight flow conduit while solving the
`aforementioned problems caused by flow splitters and
`curved conduits, has therefore not been commercially
`successful
`in Coriolis mass flow rate meter designs,
`especially for large flow conduits. This failure is due to
`the inherent imbalance of a single straight flow conduit
`in any natural bending-modes of vibration. A straight
`flow conduit fixedly mounted at both ends has a number
`of natural bending-modes of vibration wherein the cen-
`ter-line of the conduit deflects or rotates away from its
`rest position in a number of half sine-shaped waves
`along the length of the conduit. Higher frequency bend-
`ing-modes involve increasing numbers of these half
`sine-shaped waves in integer multiples. Each of these
`bending-modes causes reaction forces applied to the
`conduit mounts creating balance and accuracy prob-
`lems analogous to the single curved flow conduit mod-
`els previously described. A single straight tube design
`of this nature is disclosed in U.S. Pat. No. 4,823,614 to
`Dahlin, in which the flow tube cross-section is perma-
`nently deformed in several locations as shown in its
`FIGS. 2A—2D to enhance its bending in a “higher-
`mode” such as its FIG. 3B. The higher modes of vibra-
`tion as shown in the Dahlin patent FIGS. 3A—3E all
`show the flow conduit bending away from a straight
`line at its ends which will cause reaction torques and
`forces at the mounts. These reactions are not counter
`balanced and thus can create reaction forces as previ-
`ously described. Dahlin states that this embodiment can
`be used in “average” sized pipes with average being
`defined as 5 to 5,5 inch inside diameter. Although the
`reason for this size restriction is not explained, it is prob-
`ably a consequence of imbalance from using a bending-
`mode of vibration with no counter-balance apparatus.
`The unique advantages of the present invention ac-
`crue from the use of a single straight flow conduit in a
`radial-mode of vibration instead of a bending-mode as is
`currently used in the art. For clarity, the term_ “bending-
`mode” is defined as a vibration mode wherein the cen-
`ter-line or axis of the flow conduit translates and/or
`rotates away from its rest position in an oscillatory
`manner while the cross-sectional shape of the flow con-
`duit remains essentially unchanged. By contrast, the
`term “radial-mode” is defined as a vibration mode
`wherein the center-line or axis of the flow conduit re-
`mains essentially unchanged while all or a part of the
`wall of the flow conduit translates and/or rotates away
`from its rest position in an oscillatory manner. Common
`examples of radial-modes of vibration are the natural
`vibration of a bell or wine glass. In these twogexamples
`the fundamental radial-mode of vibration causes the
`normally round cross-sectional shape of the free end of
`the bell or wine glass to deflect into an oscillating ellip-
`tical shape. Since the center-line or axis of this radial-
`mode stays essentially unchanged, the stem (in the wine
`glass example) can be held without feeling or interfering
`with the vibration, exemplifying the absence of reaction
`forces at the mount. Applying this idea to the flow
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`conduit of a Coriolis mass flow rate meter, a single
`straight flow conduit is employed, fixedly attached at
`both ends, and vibrated in a radial-mode of vibration
`where the wall of the_ flow conduit translates and/or
`rotates away from its rest position in an oscillatory
`manner, and the center-line of the flow conduit remains
`essentially unchanged. The combination of fluid motion
`and radial-mode vibration causes a Coriolis force distri-
`bution along the moving wall of the flow conduit which
`alters the cross-sectional shape of the conduit as a func-
`tion of mass flow rate. This altered shape or its effects,
`are then measured as an accurate indication of mass
`flow rate. Since this radial mode of vibration causes
`substantially no net reaction forces where the conduits
`are mounted, a balanced resonant system Coriolis mass
`flow rate meter is thereby created with no flow split-
`ters, curved flow conduits, or counter-balance devices.
`In addition, a unique non-intrusive method is em-
`ployed to determine the pressure and the density of the
`fluid inside the flow conduit by simultaneously vibrat-
`ing the flow conduit in two modes of vibration. The
`values of the frequencies of the two modes of vibration
`are functionally related to both the fluid density and the
`pressure difference between the inside and the outside
`of the flow conduit.
`
`Due to the unique operation of the invention, and its
`ability to directly measure mass flow rate, fluid density,
`temperature and pressure, virtually any defined static or
`dynamic fluid parameter can be calculated such as fluid
`state, viscosity, quality, compressibility, energy flow
`rate, net flow rate, etc.
`As an alternate to using a radial-mode of vibration
`involving the entire wall of the flow conduit as previ-
`ously described, a portion of the flow conduit perimeter
`can be vibrated as necessary to generate Coriolis forces.
`This method is well suited for use in flow conduits of
`very large size and non—circular shapes where vibration
`of the e11’tire conduit is not practical. This method is also
`well suited to flow conduits formed into bulk materials
`thus having several rigid sides incapable of entire-
`perimeter radial mode vibration, such as a flow conduit
`etched into silicon or quartz to form a micro flow me-
`ter.
`
`The present invention solves the previously men-
`tioned problems caused by flow splitters, curved flow
`conduits and imbalance and allows Coriolis mass flow
`meter technology to be used in areas such as sanitary
`applications, gas flow, air flow meters for weather sta-
`tions, airplanes, low pressure air-duct systems, micro
`flow meters, liquid flow meters for residential, indus-
`trial, oceanographic and shipboard use, and many more.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`For a more complete understanding of the present
`invention, and the advantages thereof, reference is now
`made to the following descriptions taken in conjunction
`with the accompanying drawings, in which:
`FIG. 1 is a perspective view of one possible preferred
`exemplary embodiment of the present invention with a
`portion of the outer case cut away for viewing the appa-
`ratus inside;
`FIG. 2 is a cross-sectional view of the embodiment of
`FIG. 1 showing the radial-mode vibration shape of the
`flow conduit where it has reached its peak deflection in
`the vertical direction;
`FIG. 3 is a cross-sectional view of the embodiment of
`FIG. 1 showing the radial-mode vibration shape of the
`flow conduit where it has reached its undeflected center
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`position. This is also representative of the
`duits’ rest position;
`FIG. 4 is a cross-sectional view of the embodiment of
`
`flow con-
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`FIG. 16 is a block diagram of one possible configura-
`tion of circuit components used to measure mass flow
`rate according to the present invention;
`FIG. 17 is a perspective view of an alternate to the
`preferred exemplary embodiment of FIG. 1 using a
`vibrating flexible surface as part of a rectangular flow
`conduit perimeter to measure the mass flow rate in the
`conduit;
`FIG. 18 is a cross-sectional view through the embodi-
`ment of FIG. 17 showing three sequential deflected
`shapes of the vibrating flexible surface with no fluid
`flow;
`FIG. 19 is a cross-sectional View through the embodi-
`ment of FIG. 17 showing the deflected shape of the
`vibrating flexible surface due to Coriolis forces with
`fluid flowing through the flow conduit;
`FIG. 20 is a graph of the frequency response curve
`and is representative of the absolute value of equation
`No. 1;
`FIG. 21 is a representation of the Coriolis force distri-
`bution along the top and bottom surfaces of the flow
`conduit resulting from driving the flow conduit in a
`mode shape similar to that shown in FIG. 9;
`FIG. 22 is an alternate exemplary embodiment of the
`present invention employing a flow conduit that has
`several rigid sides and a flexible surface that is vibrated;
`FIG. 23A is a representation of the signals from the
`motion detectors of FIG. 1, and their sum with one of
`the signals inverted and with no flow through the flow
`conduit;
`FIG. 23B is a representation of the signals from the
`motion detectors of FIG. 1, and their sum with one of
`the signals inverted and with flow through the flow
`conduit;
`FIG. 24 is a cross-sectional view of an exemplary
`stress decoupling joint used to eliminate axial stress
`from the flow conduit;
`FIG. 25 is an alternate exemplary embodiment of the
`present invention employing a plurality of motion de-
`tectors, vibration isolation means, and axial stress reduc-
`tion means;
`FIG. 26 is a block diagram of one possible configura-
`tion of circuit components used to measure the mass
`flow rate of fluid and other parameters according to the
`present invention;
`FIG. 27 is a representation of various wave forms
`that can be attained at various points in the circuit of
`FIG. 26;
`FIG. 28 is a cross sectional view through the motion
`drivers of the embodiment of FIG. 25;
`FIG. 29 is an alternate arrangement of motion drivers
`to that shown in FIG. 28, using three motion drivers
`instead of two;
`FIG. 30 is an alternate arrangement of motion drivers
`to that shown in FIG. 28, using four motion drivers
`instead of two;
`FIG. 31 is a representation of the primary radial vi-
`bration motion induced by the motion drivers on the
`embodiment of FIG. 25, at a point in time when the
`flow conduit is elliptically elongated in the vertical
`direction;
`FIG. 32 is a representation of the primary radial vi-
`bration motion induced by the motion drivers on the
`embodiment of FIG. 25, at a point in time when the
`flow conduit is elliptically elongated in the horizontal
`direction;
`FIG. 33 is a representation of the secondary bending
`vibration motion induced by the motion drivers on the
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`FIG. 1 showing the radial-mode vibration shape of the
`flow conduit where it has reached its peak deflection in 5
`the horizontal direction;
`FIG. 5 is a cross-sectional view along section A—A
`in FIG. 2 showing the elliptical cross-sectional shape of
`the flow conduit at its peak deflection in the vertical
`direction;
`FIG. 6 is a cross-sectional view along section A—A
`of FIG. 3 showing the circular cross-sectional shape of
`the flow conduit as it passes through. its undeflected
`center position;
`FIG. 7 is a cross-sectional view along section A—-A 15
`in FIG. 4 showing the elliptical cross-sectional shape of
`the flow conduit at its peak deflection in the horizontal
`direction;
`FIG. 8 is a graph of the Coriolis force distribution 20
`that would be created along the top and bottom surfaces
`of the flow conduit from mass flow rate, as the flow
`conduit passes through its undeflected center position as
`in FIG. 3;
`FIG. 9 is a cross-sectional view similar to that of 25
`FIG. 3 showing greatly exaggerated representative
`deflections of the flow conduit resulting from the Cori-
`olis force distribution shown in FIG. 8;
`FIG. 9A is a cross-sectional view along section B—B
`of FIG. 9 showing the deformation of the cross-sec-
`tional shape of the flow conduit (greatly exaggerated)
`due to Coriolis forces, as the flow conduit passes
`through its center (normally undeformed) position;
`FIG. 9B is a cross-sectional view along section A—A
`of FIG. 9 showing essentially no deformation of the
`cross-sectional shape of the flow conduit due to Coriolis
`forces, as the flow conduit passes through its center
`position;
`FIG. 9C is a cross-sectional view along section C~—C
`of FIG. 9 showing the deformation of the cross-sec-
`tional shape of the flow conduit (greatly exaggerated)
`due to Coriolis forces, as the flow conduit passes
`through its center (normally undeformed) position;
`FIG. 10 is a cross-sectional representation of the
`two-lobe radial-mode vibration of the flow conduit in
`the preferred exemplary embodiment of FIG. 1 shown
`with three sequential deflected shapes (peak vertical,
`undeflected, peak horizontal) superimposed on each
`other;
`FIG. 11 is a cross-sectional representation of an alter-
`nate radial-mode of vibration to that shown in FIG. 10
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`with three sequential deflected shapes superimposed on
`each other;
`FIG. 12 is cross-sectional representation of an alter-
`nate radial-mode of vibration to that shown in FIG. 10
`with two sequential deflected shapes superimposed on
`each other;
`FIG. 13 is cross-sectional representation of an alter-
`nate radial-mode of vibration to that shown in FIG. 10
`
`with two sequential deflected shapes superiniposed on
`each other;
`’
`FIG. 14 is a representation of the time relationship of
`signals from the motion detectors of FIG. 1 with no
`fluid flowing through the flow conduit;
`FIG. 15 is a representation of the time relationship of
`signals from the motion detectors of FIG. 1 with fluid
`flowing through the flow conduit;
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`embodiment of FIG. 25, at a point in time when the
`flow conduit is vertically deflected above-its center
`position;
`FIG. 34 is a representation of the primary radial vi-
`bration motion that could be induced by the three mo-
`tion driver arrangement of FIG. 29, at a point in time
`when the motion drivers have reached their maximum
`radial excursion;
`FIG. 35 is a representation of the primary radial vi-
`bration motion that could be induced by the three mo-
`tion driver arrangement of FIG. 29, at a point in time
`when the motion drivers have reached their minimum
`radial excursion;
`FIG. 36 is a representation of the secondary bending
`vibration motion that could be induced by the three
`motion driver arrangement of FIG. 29 at a point in time
`when the flow conduit is vertically deflected above its
`center position;
`FIG. 37 is a representation of the primary radial vi-
`bration motion that could be induced by the four mo-
`tion driver arrangement of FIG. 30, at a point in time
`when the motion drivers have reached their maximum
`radial excursion;
`FIG. 38 is a representation of the primary radial vi-
`bration motion that could be induced by the four mo-
`tion driver arrangement of FIG. 30, at a point in time-
`when the motion drivers have reached their minimum
`radial excursion;
`FIG. 39 is a representation of the secondary bending
`vibration motion that could be induced by the four
`motion driver arrangement of FIG. 30, at a point in time
`when the flow conduit is vertically deflected above its
`center position;
`FIG. 40 is a representation of an alternate exemplary
`embodiment to that of FIG. 25 using a slip joint and seal
`arrangement instead of a flexible joint arrangement;
`FIG. 41 is a exemplary representation of the embodi-
`ment of FIG. 25 showing the flow conduit deflected in
`its secondary bending mode of vibration. The coils have
`been removed and the magnitude of the deflection
`greatly exaggerated for clarity;
`FIG. 42 is a representation of a parallel path Coriolis
`mass flow meter tube arrangement, viewed in the X—Y
`plane;
`FIG. 43 is a cross sectional representation of the
`parallel path Coriolis mass flow meter tube arrangement
`shown in FIG. 42, viewed in the X-Z plane;
`FIG. 44 is a close up view of the motion driver ar-
`rangement shown in FIG. 43 showing radial vibratory
`motion being imparted to both tubes, taken at a point in
`time when the tubes are elliptically elongated in the
`vertical direction;
`FIG. 45 is a close up view of the motion driver ar-
`rangement shown in FIG. 43 showing radial vibratory
`motion being imparted to both tubes, taken at a point in
`time when the tubes are elliptically elongated in the
`horizontal direction;
`FIG. 46 is an exemplary representation of one possi-
`ble Coriolis force distribution that could be developed
`in the X-Y plane on the embodiment of FIG._ 25, taken
`at a point in time when the radial motion of the flow
`conduit is passing through its normally circular central
`position after having been elliptically elongated in the
`Y-direction;
`FIG. 47 is an exemplary representation of one possi-
`ble Coriolis force distribution that could be developed
`in the X-Z plane on the embodiment of FIG. 25, taken
`at a point in time when the radial motion of the flow
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`conduit is passing through its normally circular central
`position after having been elliptically elongated in the
`Y-direction;
`FIG. 48 is an exemplary repre