Case 6:12-cv-00799-JRG Document 124-5 Filed 03/07/14 Page 1 of 18 PageID #: 3763
`Case 6:12—cv—00799—JRG Document 124-5 Filed 03/07/14 Page 1 of 18 Page|D #: 3763
`
`EXHIBIT 5
`
`EXHIBIT 5
`
`
`
`

`
`Case 6:12-cv-00799-JRG Document 124-5 Filed 03/07/14 Page 2 of 18 PageID #: 3764
`
`·· Dec. 23, 1958
`
`Filed Au1. 26, 1954
`
`W. ROTH
`GYROSCOPIC MASS FLOWMETER
`
`2,865~201
`
`.4 Sheets-Sheet 1
`
`FIG. I
`
`FIG. 2
`
`FIG. 4
`
`FIG. 6
`
`FREQUENCY
`
`.
`INVENTOR.
`WILFRED. ROTH
`
`ATTOR~_E.'f.S
`
`1-l' I
`
`MM0634688
`
`

`
`Case 6:12-cv-00799-JRG Document 124-5 Filed 03/07/14 Page 3 of 18 PageID #: 3765
`
`Dec. 23, 1958 ·
`
`Filed Au1. 26, 1954
`
`W. ROTH
`GYROSCOPIC .MASS FLOWMETER
`
`2;865,201
`
`4 Sheets-Sheet 2
`
`C\1
`It)
`
`,
`
`It)
`
`1.()
`
`+
`m
`
`INVENTOR.
`WILFRED ROTH
`BY~ Ed--t
`·~~~~y~
`ATTORNEYS
`
`~JUOU"~,~·
`~
`
`MM0634689
`
`

`
`Case 6:12-cv-00799-JRG Document 124-5 Filed 03/07/14 Page 4 of 18 PageID #: 3766
`
`Dec. 23, 1958
`
`Filed Aui. 26, 1954
`
`FIG. 7
`
`W. ROTH
`GYROSCOPIC MASS FLOWMETER
`
`2,865,201
`
`4 Sheets-Sheet 3
`
`FIG. 7b
`
`6
`7c _ _j
`
`8
`
`FIG. 7c
`
`INVENTOR.
`WILFRED ROTH
`
`FIG. 7a
`
`'
`I
`I .
`I
`
`i
`
`~
`BY
`~ U-.~~-4dJ--.-.QI" ~
`ATTORNEYS
`
`r
`
`'
`
`MM0634690
`
`

`
`Case 6:12-cv-00799-JRG Document 124-5 Filed 03/07/14 Page 5 of 18 PageID #: 3767
`
`Dec. 23, 1958
`
`Filed Aui. 26, 1954
`
`W. ROTH
`GYROSCOPIC MASS FLOWMETER
`
`2,865,201
`
`4 Sheets-Sheet 4
`
`FIG. 8
`
`FREQUENCY
`
`FIG. 10
`
`FIG. 9
`
`FIG. II
`
`FIG. 12
`
`93
`
`. f
`
`(.,
`
`INVENTOR.
`WILFRED ROTH
`
`ATTORNEYS
`
`MM0634691
`
`

`
`Case 6:12-cv-00799-JRG Document 124-5 Filed 03/07/14 Page 6 of 18 PageID #: 3768
`
`United States PaterttOffice
`
`2,865,201
`Patented Dec. 23, 1958
`
`1
`
`2,865,201
`GYROSCOPIC MASS FLOWMETER
`Wilfred Roth, West Hartford, Conn.
`Application August 26, 1954, Serial No. 452,437
`30 Claims. (CI. 73....-194)
`
`5
`
`2
`strument, as described above. While the osCillation re(cid:173)
`moves the need for rotating joints,-the rotating flywheel
`is considered ]Jighly undesirable for the reasons given
`above.
`.
`It is a primary object of the present invention to proc
`vide a mass flowmeter of the gyroscopic type, wherein the
`loop is oscillated so as to avoid the need for rotating
`joints; and in whicli the need for a rotating flywheel is
`avoided. An oscillating instrument is here termed the
`10 A.-C. type. · Certain features _of the inven'tion, however,
`are applicable to a · continuously rotating instrument, here
`termed the D .-C. type. Although the apparatus of the
`invention is patticulariy useful in measuriJ:ig the mass
`flow of fluids, generally speakih.g it .is capable, with suit-
`15 able design paramet:ers; of rrieasuring the mass flow of
`any fluid-like material.: Such materials :include emui(cid:173)
`sions, slurries of solid particles -in a liquid or gaseous
`carrier, multi-phase mixtures of liquids or gases, etc:
`The invention _,viii be explained in conjunction with
`20 the accompanying drawings, and certain features will · in
`part be pointedmit anci in part be evident from the draw(cid:173)
`ings and description thereof.
`.In the drawings:
`Fig. 1 is a side view of an A .-C; mass flowmeter; Figs.
`25 la and lb are details illustrating suitable damping means;
`Fig. 2 is a view at right angles to that of Fig. 1;
`.
`Fig. 3 is a detail showing the arrangement ofthe inlet
`and outlet conduit sectrons;
`Fig. 4 shows curves to explain: the non-resonant opera(cid:173)
`~') tion of the apparatus of Figs. 1-3; .
`Fig. 5 is acircuitdiagrarn of an indicating device which
`may be used with the apparatus of Figs. 1~3;
`Fig. 6 is another embodiment of an A.-C. mass flow(cid:173)
`meter with· simplified indication;
`Fig. 7 is a further embodiment of an A.-C .. mass flow-
`meter;
`Fig. 7 a is a detail showing the iriiet and outlet con-
`duit sections;
`. .
`.
`Figs. 7 b and 7 c are · details of a torque drive which
`
`35
`
`This invention relates to mass flowmeters utilizing
`the gyroscopic principle. The invention is especially di(cid:173)
`rected to the provision of satisfactory A.-C. or oscillat(cid:173)
`ing flowmeters, as <distingl1ished from those of the D.-C.
`or continuously rotating type, although certain features
`are applicable to the latter.
`There is a considerable need in industry for an instru(cid:173)
`ment which will measure mass flow, as distinguished from
`In many industrial processes it is the mass
`volume flow.
`of a reagent that is important, rather than m erely volume.
`Also, it is often advantageous to market fluid-li"ke mate(cid:173)
`rials according to their mass rather than volume. While
`mass .flow is the product of volume flow and density, the
`den·sity may vary . depending upon the exact constituents
`of the material, and usually varies considerably with tem(cid:173)
`perature. Thus the conversion of volume flow to mass
`flow is often difficult. Even when such conversion is
`possible, it is advantageous to have an instrument which
`indicates mass flow directiy.
`It has been suggested to employ the gyroscopic prin(cid:173)
`ciple in order to measure mass flow directly. In such an
`instrument the fluid-like material is caused to flow in a
`curved conduit, specifically a conduit in the fonn of a
`loop. For a given fluid and conduit, the angular mo(cid:173)
`mentum varies with the rate of flow of the fluid thr.ough
`40 may be employed with.the apparatus of Fig. 7;
`the conduit. By virtue of the flowing fluid, the conduit
`Figs. 8 and 9 show curves illustrating the resonant op-
`is equivalent to the rotor of an ordinary gyroscope. if
`eration of the apparatus of Fig. 7;
`.
`.
`the loop is caused to rotate about an axis perpendicular
`Figs. 10 and 11 are details of an alternative form of
`to that of the. angular momentum, a torque will be pro(cid:173)
`torque drive which may be employed in the apparatus of
`If, for ex(cid:173)
`duced about the mutually · orthogonal axis.
`45 Fig; 7; and
`·
`ample, the loop is circular and· is caused to rotate about
`Fig. 12 is a dia:gtain showing a torque feedback sys(cid:173)
`a diameter thereof by a drive source, a torque or couple
`tem in accordance-with the invention.
`will be produced about an axis mutually perpendicular
`. . Referring .now to Fig. l, a fluid conduit:IO is arranged
`to the axis of rotation and the axis of the .loop. T he in(cid:173)
`in the .forhl of a loop and attached to support members
`.stantaneous value of this torque_ will be propm:tional to
`50 31, 31'.· As specifi:cally shown the loop is circular, but
`the instantaneous value of the angular inom'enttlm as de(cid:173)
`other configurations· could-be employed if desired." Inlet
`termined by the tate of mass flow of the fluid, and. the
`and outlet fluid conduit sections 11 and 12 extend. from
`instantaneous value of the angular velocity of the .loop
`adjacent points 13', 13'. of the loop to approximately the
`about the drive axis.
`·
`center of the loop: · As here shown,- conduit sections :u
`. In one instniment of this generaJtype which has been
`55 and 12 are ·of. flexible' hose a:n:d secured to the horizontal
`proposed, continuous :rotation of. the lo_op about one axis
`support member 14 by a band 15: Or, the sections H; 12
`has been employed, and a rotating mass mounted ·con(cid:173)
`can be extensions of:the tubing of'loop 10,. extending in(cid:173)
`centrically with the . axis of the ]oop has been: driven at
`wardly to the loop ax!sin the manner shown but without
`an ar1g~lar velocity .. controlled by· gyroscopic cp.uples pro(cid:173)
`the . restraining band 15; and flexible couplings attached
`duced by the flowing liquid, but in a counter direction, so
`60 to the tube sections near the center of the loop.
`that the an·gular. momentum of the flowing·liquid is coun(cid:173)
`The loop 10 is· mounted- for angular . movement with
`teracted by the angular momentum of tb,e rotating mass.
`This produces a null type instrument. · The use of. a rotat-
`respect'to member 14 by suitable means · which .are her~
`ing mass in this manner is ·considered undesirable be(cid:173)
`shown as short lengths of music wire 16, 16'. Thus, the
`cause of the added weight and complexity involved, to(cid:173)
`65 loop 10 is mounted for: angular movement about im axis
`approximately in the plane- of the loop, and the lengths
`gether withthe need.for careful maintenance. Further(cid:173)
`of music wire. form torsionill springs which produce· a-re(cid:173)
`more; a continuously rotating loop requires :sealed rotat-
`storing moment when the loop 10 is··angularly deflected oh
`ing .bearings which ate relatively expensive, require care-
`either side of the. central position illustrated,
`ful maintenance and may be troublesome with chemically
`The loop· and. its ·associated support member 14 is
`active·fluids: .or) fluids at:high pressure: . . .
`.
`.
`.
`mounted for rotation · about an . axis approximately per(cid:173)
`It has also· been· proposed ·to oscillate the loop, imd
`pendicular to-that of .rnember 14 by a member 17, here
`employ· a rotating .flywheeJ:to .'produce a null type in-
`
`70
`
`MM0634692
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`Case 6:12-cv-00799-JRG Document 124-5 Filed 03/07/14 Page 7 of 18 PageID #: 3769
`
`2,865,201
`
`3
`shown as mounted for rotation about a vertical axis by
`bearings 18, 18' in a suitable housing 19. The loop 10
`may be oscillated about the vertical axis by motor 21 and
`eccentric cam 22 bearing against a rod 23 affixed to ver(cid:173)
`tical member 17 by a collar 24. Spring means 25 is at(cid:173)
`tached at one end to rod 23 and at the other end to a
`stationary support 26 so as to hold rod 23 in engagement
`.with eccentric cam 22. For convenience of illustration,
`the point at which the spring 25 is attached to support 26
`is shown lying above the rod, but in practice it will be
`understood that the point of attachment will ordinarily
`be substantially on a line with rod 23. While an eccentric
`cam is specifically illustrated, any other suitable means
`for oscillating the loop about the vertical axis may be
`employed.
`Since a constant frequency of oscillation at the selected
`frequency of operation is desirable for accuracy, motor 21
`is advantageously of the synchronous type. Other types
`may of course be employed if due care is taken to assure
`constant speed under existing operating conditions.
`In operation, fluid is supplied to the loop through one
`of conduit sections 11, 12 and led away from the loop
`through the other section.
`In flowing through loop 10,
`the mass of the fluid creates an angular momentum which
`is proportional to the rate of mass flow of the fluid. When
`the loop is rotated about the vertical axis, a torque is
`developed about the horizontal axis of member 14 which
`is proportional to the vector product of the instantaneous
`value of the angular momentum and the instantaneous
`value of the angular velocity about the vertical axis.
`Both of these quantities have direction as well as magni(cid:173)
`tude. Hence if the direction of fluid flow or angular
`velocity is reversed, the resulting torque will be reversed.
`With a sinusoidal oscillation, as provided by the drive
`motor 21 and cam 22 in Fig. 1, the resulting torque will
`also be sinusoidal.
`The movement produced by this torque is restrained by
`music wires 16, 16' and hence the loop 10 oscillates
`about the horizontal axis at the frequency of the vertical
`oscillation and with an amplitude proportional to the rate
`of mass flow.
`A transducer is associated with the loop which is sensi(cid:173)
`tive to gyro-scopic couples produced by the loop about the
`horizontal axis of 14. As here illustrated, the transducer
`is of the velocity type so as to yield an output proportional
`to the angular velocity of the-loop about the axis of 14.
`In the form illustrated, a coil 27 is attached to the loop 10
`and a portion thereof moves in an air gap of magnet 28.
`The magnet may be of the permanent type or magnet(cid:173)
`ized by a suitable field coil. Connections 29 to the coil
`are provided so ·that the electric potential induced in the
`coil as the position of the coil in the magnetic field varies
`may be supplied to an indicating instrument.
`Although many types of transducers to measure dis(cid:173)
`placement or ·its time derivatives, or stresses, strains and
`the like, can be employed, such as resistance wire strain
`gauges, magnetostrictive strain gauges, piezoelectric strain
`gauges, differential transformers, etc., those of the veloc(cid:173)
`ity typ~ are preferred at the present time.
`In a structure of the type described, the maximum or
`peak angular displacement of the loop from its central
`position varies with the ·rate of mass flow. Also, the
`angular acceleration of the loop is a maximum at maxi(cid:173)
`mum displacement. If a transducer is employed which
`is responsive to either displacement or acceleration the
`peak in~tantaneous values of the output will occur ~hen
`the loop is at its maximum excursion from the zero or
`neutral position. This varies with each value of rate
`of mass flow. Consequently, if an output linear with rate
`of mass flow is desired, the peak displacement of the loop
`must be linear over the desired range of mass flow
`measurements. This may be difficult to achieve in prac(cid:173)
`tice since any non-linearity in the restoring moment of
`torsional springs 16, 16' or non-Iinearities els<;where in
`
`5
`
`4
`the system will impair the linearity of the transducer
`output.
`.On the other hand, the angular velocity of the loop is
`a maximum as the loop passes through the zero or neu-
`tral position. Consequently, if a transdt:cer responsive
`to the velocity of the loop is employed, the peak in(cid:173)
`stantaneous values of the output will always be produced
`at the same point in the oscillating arc of the loop, namely,
`at the zero position thereof, regardless of the rate of mass
`1 o flow therethrough. Thus, the effect of non-linearities in
`the oscillatory motion of the loop is greatly reduced or
`entirely eliminated.
`A velocity-type transducer or pick-up is particularly
`advantageous· when combined with a peak detector cir-
`15 cuit. An example of such a circuit will be described here(cid:173)
`inafter in connection with Fig. 5.
`An important aspect of the present invention lies in
`the arrangement of the conduit sections for leading fluid
`to and from the loop. Among the advantages of the ar-
`20 rangement provided is that of preventing so-called Coriolis
`forces from affecting the accuracy of measurement.
`When a pipe or conduit containing a flowing fluid is
`subjected to angular movement transverse to its axis, the
`walls of the pipe must exert a force on the flowing fluid
`25 to impart angular acceleration thereto. This is known
`as Coriolis force. The force varies with rate of mass flow
`of the fluid in the pipe, and in an apparatus of the type
`herein considered would introduce an error unless the
`force is eliminated or the apparatus designed so that the
`30 force does not affect the output.
`In the apparatus of Fig. 1, conduit section 11 rotates
`about the drive axis 17 and hence, when fluid is flowing
`outwardly from the center, a Coriolis force is present
`which is substantially in a plane perpendicular to the
`35 drive axis (horizontal plane as specifically illustrated)
`and creates a torque about the drive axis. Similarly, a
`Coriolis force is present due to fluid flow in conduit sec(cid:173)
`tion 12, but since the fluid flow is inwardly toward the
`center, the force and resulting torque about the drive
`40 axis opposes that of conduit 11. Hence, the effects of
`the tw() Coriolis forces substantially cancel arid do not
`affect the output indication.
`In the arrangement of Fig. 1 a constant velocity drive
`source is employed, that is, a drive source whose angular
`4.) velocity is relatively unaffected by the load thereon. In
`this case it is not essential that the Coriolis forces cancel,
`so long as they are effective only about the drive axis,
`since only an additional load would be imposed on the
`drive source and the output would be unaffected. This is
`;;u accomplished in Fig. 1 by leading fluid to and from the
`loop 10 by conduits substantially parallel to and closely
`adjacent the horizontal axis 14 about which the loop
`moves to produce an output signal, that is, the output
`axis of rotation. This relationship is helpful in the event
`55 that perfect cancellation of Coriolis forces is not obtained
`by the parallel counterflow feed. Rotation of the feed
`lines by 90° is of course possible with a close parallel
`counterflow arrangement, or where the unbalance in
`Coriolis force is sufficiently small for the intended appli-
`60 cation.
`An added feature is that by connecting the inlet and
`outlet conduit sections 11, 12 to external pipe lines, etc.,
`from points near the intersection of the axes of vertical
`member 17 and horizontal member 14, and by providing
`65 flexibility in the conduit sections near the intersection of
`the axes, any restraint in the freedom of the loop to oscil(cid:173)
`late due to the connections to the external pipe line, etc.
`is reduced to a very small or negligible amount, since the
`In
`moment arm about the center of rotation is small.
`70 Fig. 1 this is accomplished by employing flexible tubes or
`conduit sections 11, 12 and providing substantially right
`angle bends in the sections, as shown in Figs. 2 and 3.
`Fig. 7, to be described hereinafter, shows an alternative
`In both figures, the loop
`arrangement to the same end.
`75 structure can be dynamically balanced by adding or re-
`
`MM0634693
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`Case 6:12-cv-00799-JRG Document 124-5 Filed 03/07/14 Page 8 of 18 PageID #: 3770
`
`·s
`plotted in Fig, 4 since it is . the quantity commonly
`measured; it' being -:understood' that fx:equency is
`1
`2ir
`
`times angular velocity.
`When the driving frequency approaches the natural
`resonant frequency f' of the loop for a liquid of given
`density, a very ·targe increase in displacement is ob(cid:173)
`tained, as shown by curves 32, 32'. In Fig. 4 damping
`has been neglected so that curves 32, 32' would intersect
`at infinity. In any practical system, damping is of course
`If the
`present and will affect the shape of the curves.
`driving frequency is increased appreciably beyond the
`natural resonant frequency, the displacement lim drops
`off inversely with frequency.
`With a fluid of lower density, similar curves will be
`obtained but the natural resonant frequency will lie at a
`higher frequency such as shown at f" in Fig. 4. For a
`20 fluid of still lower density the natural resonant frequency
`will be still higher, as indicated at f'".
`As above mentioned, in accordance with one feature
`of the present invention it is contemplated applying a
`driving frequency which will be sufficiently low· com~
`pared with the natural . resonant frequency of the lo{)p
`when filled with fluid of density within a predetermined
`range so that the apparatus will operate within the region
`35 indicated in Fig. 4.
`For a given selected frequency in this range, i. e., for
`
`30
`
`moving .weight·from-member 14:on :the:•opp_osite ~ide of
`the vertiCal. axis from. the. conduit -sections,
`In an arrangementsuch as shown in fig; -1;. the:loop :10
`has a natural.re:sonant ·frequency of oscillation about the
`axis of member .14 due to the moment oLinertia of the 5
`loop and the restoring moment provided by · torsional
`springs 16, 16'.
`In. accordance with well-known · prin,
`ciples of mechanics, the moment of inertia ·of. the loop
`10 will include not only the mass and configuration of
`the conduit itself, but also the mass and location of any 10
`members associated therewith such as. the pickup coil 27
`and the inwardly projecting supports 31, 31'. Also, any
`stiffness of the conduit sections 11, 12 must be taken :into
`account along with the stiffness of the tGrsional springs
`16, 16'. Furthermore, the natural resonant · frequency 15
`of the loop 10 will be . affected by the mass of the fluid
`contained therein. While the volume of the fluid is essen(cid:173)
`tially fixed for a given instrument, the effective mass of
`the loop when filled with fluid wiil . vary with the · density
`of the fluid.
`It has been found very important to select properly
`the frequency of ·oscillation of the loop about the vertical
`axis with resp.ect to the natural resonant frequency of the
`loop about the horizontal axis in order to obtain an accu(cid:173)
`rate indication of mass flow when metering fluids of 25
`varying density, or to meter fluids . of different density
`without changing calibration.
`In accordance with one
`aspect of the invention, it is contemplated to oscillate the
`loop at a frequency which is low compared to the natural
`resonant frequency of the loop.
`.
`.
`The curves of Fig. 4 will be .helpful in understanding
`this condition of operation. Fig. 4 shows three sets.of
`curves 32, 32', 33, 33' and 34, 34' for fluids of different
`density. Frequency of oscillation is plotted along the
`horizontal axis and .peak angular. displacement 11m. about 35
`axis o.f 14 is plotted for the vertical axis. The conditions
`plotted are for equal rates of mass flow.
`Analysis of a system such as that shown· in Fig. l indi•
`cates that the displacement II can be represented .approxi(cid:173)
`mately by the following equation:
`
`small compared to unity, Equation 1 indicates that the
`maxirimm angular displacement will be proportional to
`the mass flow.
`The selection of a particular operating frequency will,
`of course, depend upon the design parameters of the ap(cid:173)
`paratus and the range of fluid densities over which it is
`desired to employ the instrument. It will .be understood
`40 that a portion of the moment of inertia of the loop struc(cid:173)
`ture will be that due to the material of which the loop
`is constructed, and the remainder will be contributed by
`the mass of the fluid therein. Thus, only a fraction of
`the total moment of inertia will be subject to change by
`45 variations in fluid density. The torque per se about the
`axis of member 14 will be unaffected by the moment of
`inertia of the loop structure, since it is a function of rate
`of mass flow through the loop. However, the displace(cid:173)
`merit of the loop abotlt the axis of member 14, and the
`50 resulting angular velocity and acceleration, will be af(cid:173)
`fected by the moment of inertia of the loop structure.
`Thus with a pickup transducer sensitive to . one of these
`quantities, the greater the fixed component of inertia, the
`less the output of the transducer will be affected by
`55 changes in the fluid density; Of course, it is not desirable
`to make the loop structure too massive, since the sensi(cid:173)
`tivity of the instrument \Vill be reduced or more amplifi(cid:173)
`cation required, more driving poWer will be required, a ad
`greater acceleration forces will be encountered.
`
`6° For a given field of use; the variation in density of
`
`(1)
`
`where ll=angular displacement in radians of loop 10
`about axis of 14.
`'
`g=acceleratiori o.f gravity
`W=pounds of material flowing across any cross-section
`!=time in seconds
`.
`R=radius of the loop in feet
`cp=maximuril angular displacement of loop 10 about axis
`of 17 due to the constant velocity driving source in
`radians
`w=angular velocity of the constant velocity driving source
`in radians/se.c.
`.
`. .
`.
`kx=spring constant. of t~e constraint about the· torque
`axis 14 in lbAt./radhirt.
`_
`.. . . . .
`wx=natural resonant an,gular· velocitY .·· of the loop. 10
`about the torque axis 14.
`The maximum or peak angular disphicement;: lim, is
`·
`, -
`.
`given by Equation I when ei•t= I.
`This analysis indicates, · as will be noted from Equatwn
`l, that the maximum angular displacement .of the loop
`10, when driven by a constant velocity source such· as
`·motor 21, varies . linearly with · the driving angular ve(cid:173)
`locity w regardless of .the value of density at· low driving.
`frequencies where the quantity · ·
`
`w2 ·
`
`65
`
`liquids likely to be encountered is not so great as to pre(cid:173)
`clude the selection of a proper driving frequency which
`will give accurate indications and adequately high output
`signal.
`·
`It ·has been mentioned that damping inherent in any
`. practical syste111 will affect the shape of the curves of Fig.
`4. Where desired, damping can be introduced inten(cid:173)
`tionally so as to increase the frequency range of region
`70 35. Such damping can be i'ntroduced at 16, 16' by in(cid:173)
`serting viscous material, by employing dash pots between
`loop 10 and the vertical member i7, by employing elec(cid:173)
`trical damping. such as eddy current damping, etc. These
`and many other forms of damping are well known in the
`art.
`
`'
`
`.
`
`wx_2
`
`'
`
`...
`is small compared to unity. This Is the region 35-sliown
`jn Fig." 4 .
`. Frequency, father .than angular velocity, is 75
`
`~-
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`Case 6:12-cv-00799-JRG Document 124-5 Filed 03/07/14 Page 9 of 18 PageID #: 3771
`
`V=kR'do
`dt
`
`30
`
`8
`wave corresponding to the peak values of the signal in coil
`Illustrative of the foregoing, Figs .. la and lb show eddy
`27. If the rate of mass flow is constant, a constant D.-C.
`current and viscous damping, respectively. In Fig. la an
`electrically conductive metal plate 96 is secured to loop
`value wilr"be obtained at 45, and as the rate of mass flow
`varies the voltage at point 45 will likewise vary.
`10 and arranged to oscillate in the field of a magnet 97
`Tile detector output at point 45 is supplied to a thermi-
`which may be of the permanent magnet type or energized 5
`onic vacuum tube 46 connected as a cathode fol'owcr,
`by a suitable coil. Magnet 97 is stationary with respect
`to member 14 and is attached thereto by support mem-
`and the voltage across cathode resistor 47 is supplied to
`one terminal of a micro-ammeter 48. Ammeter 48 may
`ber 98. As the conductive plate 96 moves in the field
`be shunted by a variable resistance 49 for calibration
`of magnet 97, eddy currents are created in plate 96 and
`damp the movement of the loop 10. Advantageously the 10 purposes. In order to make the ind:cator insensitive to
`plate 96 is mounted on loop 10 diametrically opposite the
`line voltage variations and also to provide for setting the
`transducer coil 27 (Fig. I) so as to lie in a plane per-
`zero of meter 48, another tube 51 is provided wh:ch
`pendicular to the plane of the loop and passing through
`has its anode energized from the same B+ sour:;! as tube
`the axis of vertical member 17, as shown.
`46, and its grid supplied with a constant positive bias
`In. Fig. lb a plate 99 is attached to the loop 10 in a 15 from the same B+ source thr-ough the voltage divider
`resistors 52, 53. The cathode circuit of tube 51 includes
`manner similar to plate 96 of Fig. Ia. In this figure, the
`plate 99 is arranged to oscillate in a container Hll . filled
`resistors 54, 54' and potentiometer 55 whose total re-
`with a viscous liquid, such as a viscous oil, and the con-
`sistance is advantageously approximately equal to that
`tainer is attached to member 14 similar to magnet 97 in
`of resistor 47. The other side of meter 48 is then con-
`Fig. la. As plate 99 moves back and forth, it will shear 20 nected to the cathode of tube 51. The lower terminal of
`the viscous liquid and hence dissipate energy.
`x:ectifier 43 is returned to a variable tap on potentiom-
`While variations in the displacement Om with mass flow
`eter 55, as shown, so that an adjustable D.-C. bias can be
`may be measured by a suitable transducer and used to
`applied to the rectifier.
`indicate mass flow, as above pointed out it is advantageous
`Before making a measurement of mass flow, the zero
`to employ a velocity-type transducer. The output of such 25 of meter 48 can be set by adjusting the arm of potenti-
`cmeter 55. This impresses a positive bias on the grid
`a transducer will be proportional to the time rate of
`change of B rather than B directly.
`on tube 46 through rectifier 43 and the re,istance of
`Thus:
`filter 44. The bias is so adjusted that the difference in
`potential between the cathodes of tubes 46 and 51 re(cid:173)
`sults in sufficient current through meter 48 to bring the
`pointer to the zero setting. Thereafter the pcsit:on of
`the pointer will vary with the rate of mass flow. Meter
`38 may be calibrated in arbitrary units or directly in
`terms of rate of ma~s flow for a given instrument.
`As before pointed out, it is advantageous in a m1ss
`flowmeter such as shown in Fig. 1 to employ a trans(cid:173)
`ducer of the velocity type which gives voltage peaks at
`the neutral axis which are proportional to rate of mass
`flow. Thus, the effect Gf possible non-linearities in the
`40 osci!lation of the fluid conduit loop are relatively unim(cid:173)
`portant. Since the indicator of Fig. 5 employs peak
`deteGtion, the meter 48 is sensitive cnly to variations
`in the peak amplitude of the applied wave and v.aria(cid:173)
`tions in the instantaneous voltage between peaks are un-
`,1J important. Thus, with relatively simple instrumentation
`an accurate indication of rate of mass flow is obta'nable.
`The circuit arrangement of Fig. 5 is given merely as
`an example of a suitable arrangement employing peak
`dete·ction which has been found satisfactory in practice.
`50 However, many other circuits are known in the art em(cid:173)
`ploying peak detection and any suitable fo rm can be em(cid:173)
`ployed if · desired. Also, with adequate lin2arity in the
`-oscillation of the fluid conduit loop, or w:th transducers
`other than those of the velocity type, other forms of de-
`55 teeters can, of course, be employed.
`If the integrated mass flow is desired, rather than the
`instantaneous rate of mass flow, a suitable form of inte(cid:173)
`grating indicator 'can be employed in place of meter 48.
`For example, a watt-hour meter with one coil connected
`00 in place of meter 48 and the other coil energized from
`a constant voltage source could be employed.
`For less stringent applications the displacement of the
`loop may be indicated directly, as by means of a pointer,
`rather than employing apickup transducer and associated
`tlJ circuitry such as described above.
`Fig. 6 illustrates such an arrangement, together with a
`loop and mounting arrangement which,. although not pos(cid:173)
`sessing all the advantages of that shown in Fig. 1, may
`nevertheless be employed in some applications. Here the
`iO loop 10 is mounted for rotation about a diameter thereof
`by bearings 56, 56' · carried ·by a U -shaped frame 57.
`Frame 57 is mounted for rotation about an axis perpen(cid:173)
`dicular to that of bearings 56, 56' by shaft 58 rotating
`in bearing housing 58'. The loop may be oscillated about
`75 the axis of 58 in the saine manner as in Fig. 1.
`
`where
`V=voltage output of the transducer
`k=a constant dependent on design of the transducer
`R'=~distance of the pickup from the axis 14 of rotation 35
`Curves similar to Fig. 4 may be drawn which indicate
`· the variation in output with velocity-type pickups by clif(cid:173)
`ferentiating Equation 1 and plotting the results, exclusive
`of the factor etwt. Although the shape of the curves will
`differ from those shown in Fig. 4, the conclusion as to the
`oper1lting region described above will be evident there(cid:173)
`from.
`The amplitude of oscillation in an apparatus like that
`of Fig. 1 can be made quite small. For example in one
`specific construction of an instrument designed to measure
`relatively low rates of mass flow, up to 10 pounds per
`minute, the amplitude of oscillation about the vertical axis
`was ±0.5 degrees. For a full-scale mass flow of 10
`lbs./min. the maximum displacement of the loop about
`the horizontal axis was approximately ±0.005 degree.
`The loop radius was 3.5", the operating frequency was 10
`cycles/second and the natural resonant frequency of the
`loop was 100 cycles/second. A relatively simple velocity
`pickup gave sufficient output for convenient amplification
`and indication.by a circuit similar to that shown in Fig. 5.
`Referring now to Fig. 5, a circuit is shown for receiving
`the output of apparatus such as shown in Fig. 1, and giv(cid:173)
`ing a direct indicatio-n of rate of mass flow on a suitably
`calibrated meter. In Fig. 5. coil 27 is that shown in Figs.
`1 and 2 and supplies a voltage proportional to rate of
`mass flow to the circuit. A rejection filter 41 is advan(cid:173)
`tageously employed to reject any 60-eycle power line fre- ·
`quencies. As here shov;n, it is of the so-called "twin T"
`type, but of course any suitable form of filter can be em(cid:173)
`ployed. The voltage variations from input coil 27 are
`amplified in stages including tubes 42. Any suitable low
`frequency amplifier d