CA1106636A - Method and structure for flow measurement - Google Patents
Method and structure for flow measurementInfo
- Publication number
- CA1106636A CA1106636A CA307,980A CA307980A CA1106636A CA 1106636 A CA1106636 A CA 1106636A CA 307980 A CA307980 A CA 307980A CA 1106636 A CA1106636 A CA 1106636A
- Authority
- CA
- Canada
- Prior art keywords
- conduit
- set forth
- axis
- oscillation
- shaped conduit
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/76—Devices for measuring mass flow of a fluid or a fluent solid material
- G01F1/78—Direct mass flowmeters
- G01F1/80—Direct mass flowmeters operating by measuring pressure, force, momentum, or frequency of a fluid flow to which a rotational movement has been imparted
- G01F1/84—Coriolis or gyroscopic mass flowmeters
- G01F1/8409—Coriolis or gyroscopic mass flowmeters constructional details
- G01F1/8413—Coriolis or gyroscopic mass flowmeters constructional details means for influencing the flowmeter's motional or vibrational behaviour, e.g., conduit support or fixing means, or conduit attachments
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/76—Devices for measuring mass flow of a fluid or a fluent solid material
- G01F1/78—Direct mass flowmeters
- G01F1/80—Direct mass flowmeters operating by measuring pressure, force, momentum, or frequency of a fluid flow to which a rotational movement has been imparted
- G01F1/84—Coriolis or gyroscopic mass flowmeters
- G01F1/8409—Coriolis or gyroscopic mass flowmeters constructional details
- G01F1/8427—Coriolis or gyroscopic mass flowmeters constructional details detectors
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/76—Devices for measuring mass flow of a fluid or a fluent solid material
- G01F1/78—Direct mass flowmeters
- G01F1/80—Direct mass flowmeters operating by measuring pressure, force, momentum, or frequency of a fluid flow to which a rotational movement has been imparted
- G01F1/84—Coriolis or gyroscopic mass flowmeters
- G01F1/8409—Coriolis or gyroscopic mass flowmeters constructional details
- G01F1/8431—Coriolis or gyroscopic mass flowmeters constructional details electronic circuits
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/76—Devices for measuring mass flow of a fluid or a fluent solid material
- G01F1/78—Direct mass flowmeters
- G01F1/80—Direct mass flowmeters operating by measuring pressure, force, momentum, or frequency of a fluid flow to which a rotational movement has been imparted
- G01F1/84—Coriolis or gyroscopic mass flowmeters
- G01F1/845—Coriolis or gyroscopic mass flowmeters arrangements of measuring means, e.g., of measuring conduits
- G01F1/8468—Coriolis or gyroscopic mass flowmeters arrangements of measuring means, e.g., of measuring conduits vibrating measuring conduits
- G01F1/8472—Coriolis or gyroscopic mass flowmeters arrangements of measuring means, e.g., of measuring conduits vibrating measuring conduits having curved measuring conduits, i.e. whereby the measuring conduits' curved center line lies within a plane
Landscapes
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- General Physics & Mathematics (AREA)
- Measuring Volume Flow (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Apparatus and method for mass flow measurement utilizing a substantially "U" shaped conduit mounted in a cantilever manner at the legs thereof, an oscillator to reciprocate the conduit, and a sensor for determining the Coriolis force by measurement of the force moment around an axis substantially symmetrical to the legs of the conduit.
Apparatus and method for mass flow measurement utilizing a substantially "U" shaped conduit mounted in a cantilever manner at the legs thereof, an oscillator to reciprocate the conduit, and a sensor for determining the Coriolis force by measurement of the force moment around an axis substantially symmetrical to the legs of the conduit.
Description
~l~ h~
The present invention relates generally to a flow measuring device, and more particularly to a flow measuring device in the form of a "U" shaped conduit mounted in beam-like, cantilevered, fashion and arranged to determine the density of a fluid material in the conduit, the mass flow rate therethrough, and accordingly other dependent flow parameters.
v Heretofore, flow meters of the general type with which the present invention is concerned have been known as gyro-10 scopic mass flow meters, or Coriolis force mass flow meters.
In essence, the function of both ~ypes of flow meters is based upon the same principal. Viewed in a simplified manner, Coriolis forces involve the radial movement of mass from a first point on a rotating body -to a second point. As a result of such movement, the peripheral velocity of the mass changes, i~e~, the mass is accelerated. The accelera-tion of the mass generates a force in the plane of rotation and perpendicular to the instantaneous radial movement.
Such forces are responsible for precession in gyroscopes.
20 The prior attempts to measure mass flow in this manner involved pressure sensitive bellows or other such mechanical pivoting meansO
Several sp~cific approaches have been taken in utilizing Coriolis forces to measure mass flow. For instance, the early Roth U.S. Letters Patents 2,865,201 and 3,312,512 dicclose gyroscopic flow meters employing a full loop which is continuously rotated (DC type) or oscillated (AC type).
Another flow meter utilizing substantially the same forces but avoiding reversal of flow by utilizing a less 30 than 180 "loop" is described in Sipin U~S. ~etters Patent 3,485,098. In both instances, the devices are of the so called AC type, i.e., the conduit is oscillated around an axis and fluid flowing through the conduit flows first away from the center of rotation and then towards the center of rotation thus generating Coriolis forces as a function of the fluid mass flow rate thxough the loop.
Since there is but one means of generating Coriolis forces, all of the prior art devices of the gyroscopic and Coriolis force configurations generate the same force, but specify various means for measuring such forces~ Thus, though the concept is simple and straightforward, practical results in the way of accurate flow measurement have proven elusive.
For instance, the Roth flow meters utilize transducers or gyroscopic coupling as readout means~ The gyroscopic coupling is described in Roth as being complex, and trans-ducers are defined as requiring highly flexible conduits, such as bellows. ~he latter mentioned Roth patent is pri-marily concerned with the arrangement of such flexible bellows.
Another classical approach for measuring the force proportional to mass flow involve first driving or oscillating a conduit structure through a rotational movement around an axis, and then measuring the additional energy required to drive such conduit as fluid is flowed through the conduit~
Unfortunatelyr the Coriolis forces are quite small compared ; to the driving forces and, accordingly, it is quite diffi~
cult to accurately measure such small forces in the context of the larye driving force.
Still another measurement means is described by Sipin at column 7, lines l through 23 of U.S. Letters Patent 3,485,098. In this arrangement velocity sensors independent of the driving means are mounted to measure the velocity of the conduit as a result of the distortion of the conduit caused by Coriolis forces. While there may be worthwhile information obtained by such measurements, velocity sensors require measurement of a mlnute differential velocity super-imposed upon .he very large pipe oscillation velocities.
Thus an entirely accurate determinate of the gyroscopic force must deal with velocity measurernents under limited and specialized conditions as discussed below. Mathematical analysis confirms that velocity measurements provide at best marginal results.
The present invention, which provides a heretofore unavailable improvement over previous mass flow measuring devices, comprises a support, a "U" shaped, continuous conduit solidly mounted at the open end of the "U" to the support and extending therefrom in a nonarticulated~ canti-levered fashion, means for oscillating the conduit relative to the support on either side of the static plane of the "U"
shaped conduit and about a first oscillation axis, and means to measure the Coriolis forces tending to elastically dis-tort the 1'U" shaped conduit around a second deflection axis positioned substantially equidistant between the side legs of the "U" shaped conduit and through the oscillation axis thereof.
Preferably, the oscillator i5 mounted on a separa~e arm having a natural requency substantially that of the "U"
shaped tube. Accordingly, ~he two members oscillate in opposite phase similar to the manner in which the tines of a ~ ...
tuniny fork oscillate and like a tuning fork, canc~l vibr~-tions at the suppo~t. In a particul~rly preferred embodi-ment, the distortion of the "U" shaped conduit is measured by sensors positioned adjacent the intersections of the base and legs of the conduit which measure the time lag between the leading and trailing edges of the conduit through the nominal central point of oscillation as a result of distor-tion by the Coriolis forces. This arrangement avoids the need to control the frequency and/or amplitude of oscilla-tion.
~he cantilevered beam-like mounting of the "U" shaped conduit is of more than passing significance. In the in-stance in which distortion is measured, such mounting pro-vides for the distortion resulting from the Coriolis forces to be offset substantially entirely by resilient deformation ~ within the conduit free of mechanical pivot means other than ! flexing of the conduit. Thus rather than compromising the accuracy of the flow meters by measuring but one of the opposing forces, the method and apparatus of the present invention is specfically s~ructured to minimize or obviate the forces generated by the two non-measured opposing forces, i.e., velo~ity drag and acceleration of mass. This effort has been successful to the point whexe such forces are present in cumulative quan~ities of less than .2% of the torsional spring force~ Also, by mounting the conduit in a beam-like fashion, which pivots by beam bending, the need for bellows and other such devices which are reactive to the differences in pressure between the conduit and ambient pressure are entirely avoided. Pivoting is accomplished free of pressure sensitive, separate pivot means.
Accordinglyy an advantage of the present invention is to provide a new and improved apparatus and me'chod ~or measuring mass flow which provides highly accurate measure-ment with simple, low cost construction.
Another advantage of the present invention is to pro-vide a new and improved apparatus for measuring mass flow which is substantially insensitive to pressure difference between ambient pressure and the fluid being measured.
In the Drawings:
FIGURE 1 is a perspective view of a fluid flow meter according to one embodiment of the present invention;
FIGURE 2 is an end view of the Elow meter of FIGURE 1 illustrating oscillation at midpoint under no flow condi-tions;
FIGURE 3 is an end view of the flow meter of FIGURE 1 illustrating oscillation at midpoint in the up direction under flow conditions;
FIGURE 4 is an end view of the flow meter of FIGURE 1 illustratin~ oscillation at midpoint in the down direction under flow conditions;
E`IGURE 5 is a block diagram drawing of the drive cir-cuit of the flow meter of FIGURE l;
FIGURE 6 is a logic diagram o the readout circuit of the flow meter of FIGURE l;
FIGURE 7 is a timing diagram of the readout signals of the flow meter of FIGU~E 1 undar no flow conditions;
FIGURE 8 is a timing diagram of the readout signal of the flow meter of FIGURE 1 with flow through the conduit;
FIGURE 9 is a simpliied perspec~ive view of a fluid flo~ meter according to another embodim~nt of the present invention.
EIGURE 10 is a circuit diagram of the drive and readout ., .
portion of the flow meter of FIGURE 9, with the exception of the distortion sensing portion of the circuit;
FIGURE 11 is a circuit diagram of one distortion sensing arrangement suitable to generate the signal labeled B in FIGURE 10;
FIGURE 12 is another circuit diagram for a purpose identical to that of FIGURE 11;
FIGURE 13 is yet another circuit diagram for a purpo~e identical to that of FIGURE 11; and FIGU~E 14 is a typical circuit diagram of the synchro-nous demodulator of FIGURES 10, 12 and 13.
Turning now to the drawings, wherein like components are designated by like reference numerals throughout the various figures, a flow meter device according to a first embodiment of the present invention is illustrated in FIGURE
1 and generally designated by reference numeral 10. Flow met~r 10 includes fixed support 12 having "U" shaped conduit 14 mounted thereto in a cantilever, beam-like fashion. i'U"
shaped conduit 14 i5 preferably of a tubular material having resiliency such as is normally found in such materials such a5 beryllium, copper, tempered aluminum, steel, plastics, etc. Though de~cribed as "U shapedl', conduit 14 may have legs which converge, diverge, or are skewed su~stantially.
A continuous curve is contemplated. Preferably, "U" shaped conduit 14 includes inlet 15 and outlet 16 which in turn are connected by inlet leg 18, base leg 19 and outlet leg 20.
Most preferably, inlet leg 18 and outlet leg 20 are parallel, and base leg 19 is perpendicular to both; but, as mentioned above, substantial deviations from the ideal configuration, i~eO, 5 convergence or divergence do not appreciably com-promise results. Operable results may be obtained with even gross deviations on the order of 30 or 40, but, since little is to be gained from such deviations in the embodiment of concern, it is generally preferred to maintain inlet ley 18 and outlet leg 20 in a substantially parallel relationship.
Conduit 14 may be in the form of a continuous or partial curve as is convenient.
Though the physical configuration of "U" shaped conduit 14 is not critical, the frequency characteristics are im-portant. It is critical in the embodiment of FIGURE 1 which permits distortion that the resonant frequency around axis W-W be different than that around axis o-O, and most pre-ferably that the resonant frequency about axis W-W be the lower resonant frequency~
Spring arm 22 is mounted to inlet and outlet legs 18 and 20, and carries force coil 24 and sensor coil ~3 at the end thereof adjacent base leg 19. Magnet 25, which fits within force coil 24 and sensor coil 23, is carried by base leg 19. Drive circuit 27, which will be discussed in more detail below, is provided t~ generate an amplified force in response to sensor coil 23 to drive "U" shaped conduit 14 at its natural frequency around axis W-W in an oscillating manner. Though IlU" shaped conduit 14 is mounted in a beam-like fashion to supports 12, the fact that it is oscillated at resonant freguency permits appreciable amplitude to be attained in the "beam" oscillation made around axis W-W.
"U" shaped conduit 14 essentially pivots around axis W-W at inlet 15 and outlet 1~.
As a preerable embodiment, first sensor 43 and second sensor 44 are supported at the intersectlons of base leg 19 and inlet leg 18 and outlet leg 20, respectively. Sensors 43 and 44 which are preferably optical sensors, but generally ~ ,3~ ~
proximity or center crossing sensors, are activated at "U"
shaped conduit 14 passes through a nominal reference plane at approximately the mid-point of the "beam" oscillation.
Readout circuit 33, as will be clescribed below, is provided to indicate mass flow measurements as a function of the time clifferential of the signals generated by sensors 44 and 43.
Operation of flow meter 10 will be more readily under-stood with reference to FIGURES 2, 3, and 4, which, in a simplified manner, illustrate the basic principal of the instant invention. When conduit 14 is oscillated in a no flow condition, inlet leg 18 and outlet leg 20 bend at axis W-W essentially in a pure beam mode, i.e., without torsion.
Accordingly, as shown in FIGURE 2, base leg 19 maintains a constant angular position around axis O~O throughout the oscillation. However, when flow is initiated, fluid moving radially from axis W~W through inlet leg 18 generates a first Coriolis force perpendicular to the direction of flow and perpendicular to axis W-W while flow in the outlet leg 20 generates a second Coriolis force again perpendiculax to the radial direction of flow, but in an opposite direction to that of the first Coriolis force since flow is in the opposite direction. Accordingly, as shown in FIGURE 3, as base leg 19 passes through the mid-point of the oscillation, the Coriolis forces generated in inlet leg 18 and ou~let leg 20 impose a force couple on l'U" shaped conduit 14 thereby rotating base leg lg angularly around axis O-O. The dis-tortion is both a beam bending distortion and a torsional distortion essentially in inlet leg 18 and outlet leg 20.
As a result of the choice of frequencies and the configura-tion of "U" shaped conduit 14, essentially all of ~he re-sistive force to the Coriolis force couple i9 in the nature of a resilient spring distor-tion, thereby obviating the need ; to and complication of measuring velocity drag restorative Eorces and inertial opposing forces. Given a substantially constant frequency and amplitude, measurement of the angular distortion of base leg l9 around axis O-O at the nominal midpoint of the oscillation, provides an accurate indication of mass flow. This provides a substantial improvement over c the prior art. However, as a most significant aspect of the present invention, determination of the distortion of base lO leg 19 relative to the nominal undistorted midpoint plane around axis O-O in terms of the -time difference between the instant the leading leg, i.e., the inlet leg in the case of FIGU~E 3, passes through the midpoint plane and the trailing leg, i.e., the outlet leg in the case of FIGUP~ 3, passes such plane, avoids the necessity cf maintaining constant frequency and amplitude since variations in amplitude are accompanied by compensating variations in the velocity of base leg l9. Accordingly, by merely driving "U" shaped con-duit 14 at its resonant frequency, time measurements may be 20 made in a manner which will be discussed in further detail below, without concern for concurrent regulation of ampli-tude. However, if measurements are made in but one direc-tion, i.e., the up direction in FIGURE 3, it would be necessary to maintain an accurate angular alignment of base leg l9 relative to the nominal midpoint plane. Even this require-ment may be avoided by, in essence, subtracting the time measurements in the up direction shown in FIGURE 3, and in the down direction shown in FIGURE 4. As is readily recog-nized by one skilled in the art, movement in the down direc-30 tion, as in FIGURE 4, reverses the direction of the Coriolis force couple and accordingly, as shown in FIGURE 4, reverses ~t;, ~
the direction of distortion as a result of the Coriolis force couple.
Summarily, s-tated broadly, "U" shaped conduit 14, having specified frequency charactexistics though only general physical configuration characteristics, is merely oscillated around axis W-W. Flow through "U" shaped conduit 14 induces spring distortion in "U" shaped conduit 14 resulting, as a convenient means of measurement, in angular movement of ' base leg 19 around axis O-O initially in a first angular 10 direction during one phase of the oscillation, and, then in } the opposite direction during the o~her phase of oscillat-on.
Though, by controlling amplitude, flow measurements may be made by direct measurement of distortion, i.e., strobe lighting the base leg 19 at the midpoint of oscillation with, for instance, an analogue scale fixed adjacent to end portions and a pointer carried by base leg 19, a pr~ferred mode of measurement involves determining the time difference between the instance in which the leading and trailing edges of the base leg 19 move through the midpoint plane. This 20 avoids the need to control amplitude. Further, by measuring the up oscillation distortions and the down oscillation distortions in the time measurement mode r anomalies re-~ulting from physical misalignment of "U" shaped conduit 14 relative to the midpoint plane are cancelled rom the measure-ment results.
The essentially conventional - given ~he above dis-cussion of the purposes of the invention - electronic as-pects of the invention will be more readily understood with re~erence to FIGUR~S 5 through 8.
As shown in FIGURE 5, dxive circuit 27 is a simple means for dekecting the signal generated by movement of maynet 25 in sensor coil 23. Deteetor 39 compares the voltage produced by sensor coil 23 with reference voltaye 37. As a result, the gain of force coil amplifier 41 is a function of the velocity of ma~net 25 within sensor coil 23.
Thus, the amplitude of the oseillation of "U" shaped conduit 14 is readily controlled. Sinee "U" shaped conduit 14 and spring arm 22 are permitted to oscillate at their resonant frequeneies, frequency eontrol is not required.
The circuitry of FIGURE 5 provides additional informa-tion. The output of foree eoil amplifier 41 is a sinusoidal signal at the resonant frequency of "U" shaped conduit 14.
Since the resonant frequency is determined by the spriny constant and mass of the oscillating system, and given the fact that the spring constant is fixed and the mass changes only as the density of the fluid flowing through the conduit (the eonduit mass elearly does not change), it will be appreeiated that any ehange in frequeney is a funetion of the ehanye in density of the fluid flowing through the eonduit. Thus, sinee the time period of the oseillation ean be determined, it is a simple matter to count a fixed fre-queney oseillator during the time period to determine a density faetor. Onee generatedl the density faetor can be eonverted to flu1d density by, for instanee, a ehart or graph in that the time period is not a linear funetion of density, but only a determinable funetion thereof. Should a direet readout he desired, a mieroproeessor ean be readily programmed to eonvert the density ~aetor direetly to fluid density.
The nature and funetion of readout eireuit 33 will be - 30 more readily understood with referenee to the logie eireuit illustrated in FIGURE 6, and the related timing diagrams of l ~, 3~
FIGURE 7 and 8. Readout circuit 33 is connected to inlet side sensor 43 and outlet side sensor 44 ~7hich develop signals as flags 45 and 46 carried on base leg 19 pass by the respective sensor at approximately the midpoint of plane A-A the oscillation of "U" shaped conduit 14. As shown, inlet sensor 43 is connected through inverter amplifier 47 and inverter 48 ~hile outlet side sensor 44 is similarly connected through inverter amplifier 4~ and inverter 50.
Line 52, the output from inverter 50, provides, as a result of the double inversion, a posltive signal to the set side of flip-flop 54. Similarly, line 56 provides the output from inverter 48, ayain a positive signal, the reset side of flip-flop 54. Accordingly, flip-flop 54 will be set upon output of a positive signal from sensor 44, and reset on the subsequent output of a positive signal from sensor 43.
In a similar manner, line 58 provides the inverted signal from sensor 43 through inverter amplifier 47 to the set side of flip-flop 60, while line 62 provides the output of inverter amplifier 49 to the reset side of flip-flop 60.
Thus, flip-flop 60 would be set upon the output of a negative signal from sensor 43, and r~set upon the subsequent output of a negative signal from sensor 44. The output of flip-flop 54 is connected through line 63 to a logic gate such as AND gate 64. ~ND gates 64 and 66 are both connected to the output of oscillator 67 and, accordingly, upon output from flip-flop 54, the signal from oscillator 67 is gated through AND gate 64, to line 68 and thus to the downcount side of up-down counter 70. Similarly, upon the output of a signal from flip-flop 60, the output of oscillator 67 is gated through ~ND gate 66 to line 69 connected to the upcount side of updown counter 70.
l~us, in function, readout circuit 33 provid~s a do~,m-count signal at ~he frequency of oscillator 67 to updo~
counter 70 for the period during which sensor 44 is activa-ted prlor to activation of sensor 43 during the down motion of "U" shaped conduit 14, while an upcount signal is provided to up-down counter 70 for the period during which sensor 43 is activated prior to activation of sensor 44 during the up motion of "U" shaped conduit 14.
The significance of readout circuit 33 will be more readily appreciated with referenee to the timing diagram of FIGURE 7 and FIGURE 8. In FIGURE 7, wave forms are illu~
strated ~or the condit~on in which "U" shaped conduit 14 is oscillated in a noflow condition, but in which flags 44 and 46 are not precisely s~atically aligned with plane A-A.
Thus, as shown in the timing diagram, sensor 44 initialLy switches positive early relative to the ideal time repre~ented by the vertical lines on the upstroke, and switches negative late on the down stroke as a result o~ the misalignmen~ o~
flag 46. On the other hand, sensor 43 switches positive late on the upstroke and switches negative early on the downstroke. Eowever, wh~n the outputs rom flip-flops 54 and 60 are analysed and considering further than these fllp-flops provide either downcount or upcount signals respectively to updown counter 70~ it will be seen that flip10p 54, operating on the positive or leading edge o the signals of sensors 43 a~d 44, provid~s an output on the up stroke, while, in view of the unchanged orientation flags 45 and 46, ; flip-flop 60 provides a similar output on the downstroke.
Accordingly, over a complete cycle, the up down counter 70 is first downcoun~ed a finite number of coun~s by the outp-~
of flip-flop 54, thruugh gate 64J and then upcounted an equal l`:
amount by the output of flipflop 60 through gate 66.
; Accordingly, the resulting count in up-down counter 70 is zero, representative of the no-flow condition.
On the other hand, under flow conditions as shown in FIGURE 8, sensor 43 is activated earlier than in FIGURE 7 as a result of the distortion of base leg 19 by the Coriolis force couple resulting from fluid flow, as discussed above.
Similarly, sensor 44 is activated later for an identical reason. Thus, on the upstroke, flip-flop 54 is activated for j 10 a substantially longer period than in the condition of FIGURE 7 since the misalignment of flags 45 and 46 is added to the distortion of base leg 19 by the Coriolis force couple in the up movement. On the other hand, upon down movement, i.e., generating the negative or trailing edge of the signals from sensors 43 and 44, the Coriolis force couple is reversed thus causing sensor 43 to be deactivated ~ earlier and sensor 44 to be deactivated later. Accordingly, ; flip-flop 60 is activated for a diminished period of time.
As is clear from the relative times of activation of the two 1ip-flops, the downcount period of updown counter 70 is substantially longer than the upcount period resulting from activation of flip-flop 60. The resulting increased count in the downcount sid~ of up-down counter 70 is an accurate indication of the flow over a period of oscillation. The count in up-down counter 70 after a given number of oscilla-tions is directly proportional to mass flow in "U" shaped conduit 14 during that time period. The number of oscilla-tions may be determined by, for instance, counting the number of activations of, as a typical example, flip-flop 54 at downcounter 71 connected to the output of flip-flop 54 by line 72. Thus, upon the occurrence of "N" outputs from flip-flop 54, downcounter 71 is activa'ced a~d, in turn, activates logic sequencer 74. Logic sequencer 74 is con-nected to oscillator 67, and at the frequency of oscilla or 67, first latches latch decoder driver 77 through line 78 and then resets updown counter 70 through line 75. Thus until logic sequencer 74 is again activated after "N" out-puts from flip-flop 54, display 80 indicates the accumulated count of up-down counter 70 at the time of interrogation thereof, and accordingly displays mass flow rate for the period of "N" oscillations.
Total mass flow for a selected reset period is similarly provided in that the output from up-down counter 70 is sup-plied to dlgital integrator 82 which is also connected to crystal oscillator 84. Thus the counts from updown counter 70 are integrated with re~ard to time, i.e., the fixed, stable frequency of oscillator 84, and the intergal provided to latch decoder driver 85 which in turn is connected to ~ display 87 to provide a total mass flow readout for the ; period from last activation of reset 88, i~e., a switch connected to digital integrator 82.
As described above, the density factor may also be determined independent of mass flow measurements by activating flip-flop 90 at the clock frequency of the output of flip-flop 54 through line 92. The output of flip-flop 90 is provided to AND gate 94 which, upon activation of flip-flop 90 provides the count of crystal oscillator 84 to counter latch driver 96. Thus, with time information in terms of the counts from crystal oscillator 84l and with the period of oscillation datum from flip-flop 90, available the count in counter latch driver 96 is a function of density of the fluid in "U"
shaped conduit 14, and accordingly, the readout at display 98 provides the density factor discussed above. Since the densit~ factor is not a linear function of the period of oscillation of "U" shaped conduit 14, the readout at display 98 must be further processed, either manually through a graph or through a microprocessor for density or specific gravities per se.
Summarily, it will be recognized that, in the most pre-ferred embodiment of flow meter 10 of the present invention, provides, as desired, instantaneous mass flow rate, cumulative lQ flow rate over any given period, density information as to the fluid, and volumetric flow rate if desired, i.e., by dividiny mass flow rate by density. This is accomplished, accordin~ to empirical tests, at accuracies of 0.1 ox 0.2 percent and will, for instance, measure gas flow at quite low rates in an accurate manner. There is no need to regu-late the amplitude of the frequency of flow meter 10 in the preferred embodiment, i.e., when measuring the time period between output of one sensor until the output of the other sensor.
Another embodiment of the invention is shown in FIGURE
9, whereat mass flow meter 100, which is similar in many respects to flow meter device 10, is illustrated. As shown, flow meter 100 includes a ~ase 102 and "U" shaped conduit 104 extending therefrom in a substantially solidly mounted, i.e., free of pivoting devices, manner. "U" shaped conduit - 104 includes inlet 105 and outlet 106 which communicate with inlet leg 108 and outlet leg 109, respectively. Legs 108 and 109 are arranged to pivot at points 112 and 11~
along axis W'-W' to permit oscillation of "U" shaped conduit 104 around axis W'-W'. This may be facilita~ed by, for ..~L~
instance, a thinniny in the walls of "U" shaped conduit 104 at pivots 112 and 114, but such pivot points are continllous areas of "U" shaped conduit 104 and may be unaltered tubes.
Base leg 116 connects inlet leg 108 and outlet leg 109 thus completing "U" shaped conduit 104.
Contrary to the preferred arrangement of flow meter 10, "U" shaped conduit 104 may advantageously have less resis-tance to bending around -the Coriolis force distortion axis than around oscillation axis W'-W' since Coriolis force 10 distortion is nulled. Magnets 118 carried on base leg 116 by supports 119 interact with drive coil 120 to oscillate "U" shaped conduit 104. Preferably, drive coil 120 is carried on cantilevered spring leaf 122 which is pivotally mounted adjacent axis W'-W' and of a natural frequency substantially equivalent to that of "U" shaped conduit 104 carrying the contemplated fluid therein. Of course, the mounting of magnet 118 and force coil 120 may be reversed, i.e., on conduit 104 and leaf spring 122, respectively.
Also, leaf spring 122 may he dispensed with entirely when base 102 is of substantial mass compared to the mass of "U"
shaped conduit 104 and the fluidized material flowed there~
through. However, in most instances, it is pref~rred to oscillate "U" shaped conduit 104 and leaf spring 122 at a common frequency but 180 out of phase to internally balance the forces within flow m~ter 100 and avoid vibration of base 10~ .
Base leg 116 carries magnets 125 and 126 which depend down-.7ardly therefrom. Magnet 125 is disposed within sense coil 128 mounted to base 102, while magnet 126 is similarly 30 disposed within sense coil 129 also mounted on base 102.
Magnet 125 extends within force coil 131 arranged symmetrically with sense coil 12~, while magnet 126 extends within force ; coil 132 similarly mounted relative to sense coil 129. De-flection sensing means 133 and 134, which are shown in a simplified manner in FIGURE 9, but in more de-tail in FIGU~ES
11 through 13, are positioned adjacent the intersection of inlPt legs 108 and 109 and base leg 116.
Turning now to FIGURE 10 which sets forth the circuit details not shown in FIGURE ~, it should be noted ~hat sense coils 128 and 129 are connected in series in such a manner that the movement of magnets 125 and 126 into sense coils 128 and 129 will generate a sinusoidal signal 'IA" with an amplitude proportional to the velocity of the "U" shaped conduit 104. This signal, the magnitude of which is pro-portional to the speed of movement of magnets 125 and 126, and accordingly a function of the amplitude of oscillation of "U" shaped conduit 104, is provided to AC amplifier 135, and to diode 136 which permits only the positive portion of the sinusoidal signal to charge capacitor 137. Accordingly, the input from diode 136 and capacitor 137 to differential a~plifier 138 is determined by the magnitude of the sinu-soidal signal. Differential amplifier 138 compares such input with reference voltage VRl. Thus, if the voltage of capacitor 137 exceeds VRl, amplifier 138 outpu~s a stronger signal. The output from AC amplifier 135, which i~ of cours~ a sinusoidal signal in phase with the oscillation of 'tU" shaped tube 104 and of a magnitude determined by ~he gain control outputed by differential amplifier 138, drives coil 120 to maintain the desired oscillation of "U" shaped tube 104. Signal A is also supplied to a bridge formed of resistors 140, 141, 142 and photoresistor 143. Resistor 144 i9 included in a feedback loop between resistors 140 and 142, and the output from the interconnection of resistors 140, 142 and 144 is connected to, for instance, the minus input of diffexential amplifier 145. A variable light source, such as LED 147, is connected through resistor 148 to the output of servo amplifier 150. Servo compensator 152 is ~ conventional expedient in servo systems as described in Feedback Control Systems, Analysis And Synthesis, by D'Azo and Hopuis, published by McGraw Hill, 1966, forms the feed-back loop bPtween one input of servo amplifier 150 and the output therefrom. Signal B, which is a DC signal porpor-ti~nal to the small, unnulled distortion of "U" shaped conduit 104 generated as described below with regard to FIGURES 11, 12 and 13, is connected through resistor 153 to an input of servo amplifier 150. The output of servo am-plifier 150 is referenced to voltage VR2 and connected through resistor 148 to LED 147. Thus, as a function of the magnitude of signal B with respect to VR2 driving servo amplifier 150, the intensity of LED 147 is regulated. For instance, the resistivity of photoresistor 143 decreases upon an increase in intensity of LED 147, thereby decreasing the signal supplied to the positive input of differential amplifier 145 relative to that through resistors 140 and 142 to the negative input thereof. Thus, the output of dif-ferential amplifier 145 is 180 out of phase with signal A, since the positive input thereto is decreased while the negative input is not. In summary, as signal B increases, LED 147 is dimmed and photoresistor 14 increases in resis-tivity, this causes the output of differential amplifier 145 in phase with signal A to increase. The output of differen-tial amplifier 145 is connected to force coils 131 and 132 which, as described above, are supported on base 102 and l.
r;~, :
connected in series and out o~ phase. Thus, current throug'n ~; force coils 131 and 132 crea~es, with reference to FIGI~ 9, ,.................. a torque by attracting, for instance, magnet 125 and re-' pelling magnet 126, both of which are connected to base leg . 116~ This torque across base leg 116 nulls distortion of : base leg 116 as a result of Coriolis forces generated by flow through "U" shaped conduit 104.
Resistors 155, 156 or 157 are connectable, by means of switch 159 and, to force coils 131 and 132 thereby providing a selectable load to adjust the scale factor and provide for ~ greater or lesser torque on base leg 116. The output fro~
: series connected force coils 131 and 132 are also connected as one input to synchronous demodulator 162, which will be clescribed in more detail with reference to FIGURE 14. The output of synchronous demodulator 162 is a DC signal propor-tional to mass flow rate, and accordingly provides a measure-ment of mass flow rate. A DC volt meter ~not shown) may be connected to the output of synchronous demodulator 162 to provide a visual reading of mass flow rate through "U"
shaped conduit 104 3 or the DC signal may b directly em-ployed in, for instance, a control loop to other equipment.
As shown in FIGURE 11, deflection censors 133 and 134 may comprise, or instance, left flag 164 and right flag 165 which depend from conduit 10~. Fixed let flag 166 and fixed right flag 167 are mounted on base 102. Accordingly, as base leg 116 oscillates, flags 164 and 165 will preclude light from light svurces 169 and 170 from reaching photosensors 181 and 182, respectivelyO Preferably, the point at which flags 164 and 166, and 165 and 167 intersect to block light is about at the midpoint of oscillation of base leg 116, but one set of flags may be offset somewhat from the other with regard to the interference point. It will be recognized that in the event of distortion of base leg 116 angularly relative to base 102 as a result of Coriolis forces generated by flow through "U" shaped conduit 104, a change in time lapse will exist between the occulting by flags 164 and 166 and flags 165 and 167. The time difference, and sense, will be dependent UpOIl, at a fixed oscillating rate of base leg 116, the Coriolis forces generated and the direction o~ oscillation.
Photosensor 181 is connected to flip-flop 185 at the reset side and 186 at the reset side, with the connection to flip-flop 186 being through inverter 188. Differentia~ing capaci-tors 191 and 192 are included in reset input. Similarly, photosensor 182 is connected to ~he set side of flip-flop 185 and, through inverter 189 to the set sid~ of flip-flop 186 with differentiating capacitors 193 and 194 similarly included in the inputs. Thus, as flags 164 and 166 close, a positive signal is generated by photosensor 181 which acti-vates the rese~ side of flip flop 185 and as flags 165 and 167 clo~e, a positive signal is similarly generated by photosensor 182 to aetîvate the set side of 1ip-flop 185.
Accordingly, flipflop 185 is activated for the period be-tween the closing of such sets of flags. On the other hand, the opening of flags 164 and 166, and 165 and 167, generates a falling edge, or negative signal, from photosensors 181 ~nd 182, respectively, which similarly activate flip-flop 186 through inverters 188 and 189. Accordingly, flip~flop 186 is activated for the period between the opening of one set of such flags and the other set. The outputs from flip-flop 185 and 186 are provided, through resistors 195 and 196, respectively, to the inputs of differential integrator 198. Integrating capacitor 200 is provided in associatlon with resistor 195, while integrating capacitor 201 is pro-vided in association with resistor 196 at such inputs to provide integrating capaci~y.
Ou~put signal B from di~ferential integrator 198 thus depends on the periods of activation of flip-flops 185 and 186. In the event that base leg 116 is merely oscillating without distortion, the time differences between the opening and closing of ~he flags wlll be substantially constant and the inputs to differential integrator 198 essentially identi-cal, thereby providing no signal B. On the other hand, inthe event Coriolis forces are generated, base leg 115 will be distorted in a clockwise direction on one stroke of the oscillation, and in a counter clockwise direction on the other stroke. Thus, the closing on one side of the flags will be early on one stroke and late on the other, while th~
other set of flags will be late on the firs~ stroke and early on the other. The activation of flipflops 185 and 186 therefore will not be for equal lengths of ~ime, and differ-~ntial integrator 198 will output an appropriate DC signal B
of a desired plus or minus sense depending upon the phase of the distortion of base leg 116 relative to the up/down stroke.
Another arrange~ent to provide the same result is shown i~ FIGUP~ 12. As shown, strain gages 204 and 205 are moun~ed adjacent the intersection of inlet leg 108 and base leg 116, and ouklet leg 109 and base leg 116, respectively. Strain gages 204 and 205, which may be viewed as variable resistors dependent upon the distor~ion of the adjacent portion of "U"
shaped condui~s 104, are connected with resis~ors 207 and 208 to form a bridge circuit communicating with a voltage sour~e as indicated, and connected to AC differential ampli-i,:
fi r 210. In the case of simple oscilla~ion of "U" shaped ~ conduit 104, the resistivfity of strain gages 204 and 205 ;~ vary equally thereby providlng essentially identical inputs to AC differential amplifier 210. However, in the event of distortion due to Coriolis forces, one of strain gages 204 and 205 will increase in resistivity while the other de-.:
creases thereby providing different inputs to AC differen-tial amplifier 210 and providing an output in the form of an AC signal proportional in magnitude and sense to the dif-10 ferent strains imposed upon strain gages 204 and 205.
The output from AC differential amplifier 210 is pro-vided to synchronous demodulator 211, which, in conjunction with signal A, provides a DC output propor~ional in mag-nitude and sense to the distortion of "U" shaped conduit 104 as a result of Coriolis forces. Synchronous demodulator 211 is similar to above~described synchronous demodulator 162, which will be described in more detail wi~h reference to ;~ FIGURE 14.
: A somewhat similar arrangemen~ for generating signal B
is illustrated in FIGURE 13. In this instance, however, pivot member 215 is mounted centrally on base leg 116 and carries inertia bar 217 which is free ~o rotate around pivot ~! member 215 and balanced thereon. Crystals 219 and 220 are connected between inertia bar 217 and ba~e leg 116. Thus, if base leg 116 undergoes simple oscillation, inertia bar 217 merely follows the o~cillation without a tendency to rotate around pivot member 215. How~ver, in the event of distortion of "U" shaped conduit 104 as a resul~ of Coriolis forces, base leg 116 tends to rotate relative to inertia bar 217, thereby imposing forces in opposite directions upon ; crystal 219 and 220 and thus generating, as a result of
The present invention relates generally to a flow measuring device, and more particularly to a flow measuring device in the form of a "U" shaped conduit mounted in beam-like, cantilevered, fashion and arranged to determine the density of a fluid material in the conduit, the mass flow rate therethrough, and accordingly other dependent flow parameters.
v Heretofore, flow meters of the general type with which the present invention is concerned have been known as gyro-10 scopic mass flow meters, or Coriolis force mass flow meters.
In essence, the function of both ~ypes of flow meters is based upon the same principal. Viewed in a simplified manner, Coriolis forces involve the radial movement of mass from a first point on a rotating body -to a second point. As a result of such movement, the peripheral velocity of the mass changes, i~e~, the mass is accelerated. The accelera-tion of the mass generates a force in the plane of rotation and perpendicular to the instantaneous radial movement.
Such forces are responsible for precession in gyroscopes.
20 The prior attempts to measure mass flow in this manner involved pressure sensitive bellows or other such mechanical pivoting meansO
Several sp~cific approaches have been taken in utilizing Coriolis forces to measure mass flow. For instance, the early Roth U.S. Letters Patents 2,865,201 and 3,312,512 dicclose gyroscopic flow meters employing a full loop which is continuously rotated (DC type) or oscillated (AC type).
Another flow meter utilizing substantially the same forces but avoiding reversal of flow by utilizing a less 30 than 180 "loop" is described in Sipin U~S. ~etters Patent 3,485,098. In both instances, the devices are of the so called AC type, i.e., the conduit is oscillated around an axis and fluid flowing through the conduit flows first away from the center of rotation and then towards the center of rotation thus generating Coriolis forces as a function of the fluid mass flow rate thxough the loop.
Since there is but one means of generating Coriolis forces, all of the prior art devices of the gyroscopic and Coriolis force configurations generate the same force, but specify various means for measuring such forces~ Thus, though the concept is simple and straightforward, practical results in the way of accurate flow measurement have proven elusive.
For instance, the Roth flow meters utilize transducers or gyroscopic coupling as readout means~ The gyroscopic coupling is described in Roth as being complex, and trans-ducers are defined as requiring highly flexible conduits, such as bellows. ~he latter mentioned Roth patent is pri-marily concerned with the arrangement of such flexible bellows.
Another classical approach for measuring the force proportional to mass flow involve first driving or oscillating a conduit structure through a rotational movement around an axis, and then measuring the additional energy required to drive such conduit as fluid is flowed through the conduit~
Unfortunatelyr the Coriolis forces are quite small compared ; to the driving forces and, accordingly, it is quite diffi~
cult to accurately measure such small forces in the context of the larye driving force.
Still another measurement means is described by Sipin at column 7, lines l through 23 of U.S. Letters Patent 3,485,098. In this arrangement velocity sensors independent of the driving means are mounted to measure the velocity of the conduit as a result of the distortion of the conduit caused by Coriolis forces. While there may be worthwhile information obtained by such measurements, velocity sensors require measurement of a mlnute differential velocity super-imposed upon .he very large pipe oscillation velocities.
Thus an entirely accurate determinate of the gyroscopic force must deal with velocity measurernents under limited and specialized conditions as discussed below. Mathematical analysis confirms that velocity measurements provide at best marginal results.
The present invention, which provides a heretofore unavailable improvement over previous mass flow measuring devices, comprises a support, a "U" shaped, continuous conduit solidly mounted at the open end of the "U" to the support and extending therefrom in a nonarticulated~ canti-levered fashion, means for oscillating the conduit relative to the support on either side of the static plane of the "U"
shaped conduit and about a first oscillation axis, and means to measure the Coriolis forces tending to elastically dis-tort the 1'U" shaped conduit around a second deflection axis positioned substantially equidistant between the side legs of the "U" shaped conduit and through the oscillation axis thereof.
Preferably, the oscillator i5 mounted on a separa~e arm having a natural requency substantially that of the "U"
shaped tube. Accordingly, ~he two members oscillate in opposite phase similar to the manner in which the tines of a ~ ...
tuniny fork oscillate and like a tuning fork, canc~l vibr~-tions at the suppo~t. In a particul~rly preferred embodi-ment, the distortion of the "U" shaped conduit is measured by sensors positioned adjacent the intersections of the base and legs of the conduit which measure the time lag between the leading and trailing edges of the conduit through the nominal central point of oscillation as a result of distor-tion by the Coriolis forces. This arrangement avoids the need to control the frequency and/or amplitude of oscilla-tion.
~he cantilevered beam-like mounting of the "U" shaped conduit is of more than passing significance. In the in-stance in which distortion is measured, such mounting pro-vides for the distortion resulting from the Coriolis forces to be offset substantially entirely by resilient deformation ~ within the conduit free of mechanical pivot means other than ! flexing of the conduit. Thus rather than compromising the accuracy of the flow meters by measuring but one of the opposing forces, the method and apparatus of the present invention is specfically s~ructured to minimize or obviate the forces generated by the two non-measured opposing forces, i.e., velo~ity drag and acceleration of mass. This effort has been successful to the point whexe such forces are present in cumulative quan~ities of less than .2% of the torsional spring force~ Also, by mounting the conduit in a beam-like fashion, which pivots by beam bending, the need for bellows and other such devices which are reactive to the differences in pressure between the conduit and ambient pressure are entirely avoided. Pivoting is accomplished free of pressure sensitive, separate pivot means.
Accordinglyy an advantage of the present invention is to provide a new and improved apparatus and me'chod ~or measuring mass flow which provides highly accurate measure-ment with simple, low cost construction.
Another advantage of the present invention is to pro-vide a new and improved apparatus for measuring mass flow which is substantially insensitive to pressure difference between ambient pressure and the fluid being measured.
In the Drawings:
FIGURE 1 is a perspective view of a fluid flow meter according to one embodiment of the present invention;
FIGURE 2 is an end view of the Elow meter of FIGURE 1 illustrating oscillation at midpoint under no flow condi-tions;
FIGURE 3 is an end view of the flow meter of FIGURE 1 illustrating oscillation at midpoint in the up direction under flow conditions;
FIGURE 4 is an end view of the flow meter of FIGURE 1 illustratin~ oscillation at midpoint in the down direction under flow conditions;
E`IGURE 5 is a block diagram drawing of the drive cir-cuit of the flow meter of FIGURE l;
FIGURE 6 is a logic diagram o the readout circuit of the flow meter of FIGURE l;
FIGURE 7 is a timing diagram of the readout signals of the flow meter of FIGU~E 1 undar no flow conditions;
FIGURE 8 is a timing diagram of the readout signal of the flow meter of FIGURE 1 with flow through the conduit;
FIGURE 9 is a simpliied perspec~ive view of a fluid flo~ meter according to another embodim~nt of the present invention.
EIGURE 10 is a circuit diagram of the drive and readout ., .
portion of the flow meter of FIGURE 9, with the exception of the distortion sensing portion of the circuit;
FIGURE 11 is a circuit diagram of one distortion sensing arrangement suitable to generate the signal labeled B in FIGURE 10;
FIGURE 12 is another circuit diagram for a purpose identical to that of FIGURE 11;
FIGURE 13 is yet another circuit diagram for a purpo~e identical to that of FIGURE 11; and FIGU~E 14 is a typical circuit diagram of the synchro-nous demodulator of FIGURES 10, 12 and 13.
Turning now to the drawings, wherein like components are designated by like reference numerals throughout the various figures, a flow meter device according to a first embodiment of the present invention is illustrated in FIGURE
1 and generally designated by reference numeral 10. Flow met~r 10 includes fixed support 12 having "U" shaped conduit 14 mounted thereto in a cantilever, beam-like fashion. i'U"
shaped conduit 14 i5 preferably of a tubular material having resiliency such as is normally found in such materials such a5 beryllium, copper, tempered aluminum, steel, plastics, etc. Though de~cribed as "U shapedl', conduit 14 may have legs which converge, diverge, or are skewed su~stantially.
A continuous curve is contemplated. Preferably, "U" shaped conduit 14 includes inlet 15 and outlet 16 which in turn are connected by inlet leg 18, base leg 19 and outlet leg 20.
Most preferably, inlet leg 18 and outlet leg 20 are parallel, and base leg 19 is perpendicular to both; but, as mentioned above, substantial deviations from the ideal configuration, i~eO, 5 convergence or divergence do not appreciably com-promise results. Operable results may be obtained with even gross deviations on the order of 30 or 40, but, since little is to be gained from such deviations in the embodiment of concern, it is generally preferred to maintain inlet ley 18 and outlet leg 20 in a substantially parallel relationship.
Conduit 14 may be in the form of a continuous or partial curve as is convenient.
Though the physical configuration of "U" shaped conduit 14 is not critical, the frequency characteristics are im-portant. It is critical in the embodiment of FIGURE 1 which permits distortion that the resonant frequency around axis W-W be different than that around axis o-O, and most pre-ferably that the resonant frequency about axis W-W be the lower resonant frequency~
Spring arm 22 is mounted to inlet and outlet legs 18 and 20, and carries force coil 24 and sensor coil ~3 at the end thereof adjacent base leg 19. Magnet 25, which fits within force coil 24 and sensor coil 23, is carried by base leg 19. Drive circuit 27, which will be discussed in more detail below, is provided t~ generate an amplified force in response to sensor coil 23 to drive "U" shaped conduit 14 at its natural frequency around axis W-W in an oscillating manner. Though IlU" shaped conduit 14 is mounted in a beam-like fashion to supports 12, the fact that it is oscillated at resonant freguency permits appreciable amplitude to be attained in the "beam" oscillation made around axis W-W.
"U" shaped conduit 14 essentially pivots around axis W-W at inlet 15 and outlet 1~.
As a preerable embodiment, first sensor 43 and second sensor 44 are supported at the intersectlons of base leg 19 and inlet leg 18 and outlet leg 20, respectively. Sensors 43 and 44 which are preferably optical sensors, but generally ~ ,3~ ~
proximity or center crossing sensors, are activated at "U"
shaped conduit 14 passes through a nominal reference plane at approximately the mid-point of the "beam" oscillation.
Readout circuit 33, as will be clescribed below, is provided to indicate mass flow measurements as a function of the time clifferential of the signals generated by sensors 44 and 43.
Operation of flow meter 10 will be more readily under-stood with reference to FIGURES 2, 3, and 4, which, in a simplified manner, illustrate the basic principal of the instant invention. When conduit 14 is oscillated in a no flow condition, inlet leg 18 and outlet leg 20 bend at axis W-W essentially in a pure beam mode, i.e., without torsion.
Accordingly, as shown in FIGURE 2, base leg 19 maintains a constant angular position around axis O~O throughout the oscillation. However, when flow is initiated, fluid moving radially from axis W~W through inlet leg 18 generates a first Coriolis force perpendicular to the direction of flow and perpendicular to axis W-W while flow in the outlet leg 20 generates a second Coriolis force again perpendiculax to the radial direction of flow, but in an opposite direction to that of the first Coriolis force since flow is in the opposite direction. Accordingly, as shown in FIGURE 3, as base leg 19 passes through the mid-point of the oscillation, the Coriolis forces generated in inlet leg 18 and ou~let leg 20 impose a force couple on l'U" shaped conduit 14 thereby rotating base leg lg angularly around axis O-O. The dis-tortion is both a beam bending distortion and a torsional distortion essentially in inlet leg 18 and outlet leg 20.
As a result of the choice of frequencies and the configura-tion of "U" shaped conduit 14, essentially all of ~he re-sistive force to the Coriolis force couple i9 in the nature of a resilient spring distor-tion, thereby obviating the need ; to and complication of measuring velocity drag restorative Eorces and inertial opposing forces. Given a substantially constant frequency and amplitude, measurement of the angular distortion of base leg l9 around axis O-O at the nominal midpoint of the oscillation, provides an accurate indication of mass flow. This provides a substantial improvement over c the prior art. However, as a most significant aspect of the present invention, determination of the distortion of base lO leg 19 relative to the nominal undistorted midpoint plane around axis O-O in terms of the -time difference between the instant the leading leg, i.e., the inlet leg in the case of FIGU~E 3, passes through the midpoint plane and the trailing leg, i.e., the outlet leg in the case of FIGUP~ 3, passes such plane, avoids the necessity cf maintaining constant frequency and amplitude since variations in amplitude are accompanied by compensating variations in the velocity of base leg l9. Accordingly, by merely driving "U" shaped con-duit 14 at its resonant frequency, time measurements may be 20 made in a manner which will be discussed in further detail below, without concern for concurrent regulation of ampli-tude. However, if measurements are made in but one direc-tion, i.e., the up direction in FIGURE 3, it would be necessary to maintain an accurate angular alignment of base leg l9 relative to the nominal midpoint plane. Even this require-ment may be avoided by, in essence, subtracting the time measurements in the up direction shown in FIGURE 3, and in the down direction shown in FIGURE 4. As is readily recog-nized by one skilled in the art, movement in the down direc-30 tion, as in FIGURE 4, reverses the direction of the Coriolis force couple and accordingly, as shown in FIGURE 4, reverses ~t;, ~
the direction of distortion as a result of the Coriolis force couple.
Summarily, s-tated broadly, "U" shaped conduit 14, having specified frequency charactexistics though only general physical configuration characteristics, is merely oscillated around axis W-W. Flow through "U" shaped conduit 14 induces spring distortion in "U" shaped conduit 14 resulting, as a convenient means of measurement, in angular movement of ' base leg 19 around axis O-O initially in a first angular 10 direction during one phase of the oscillation, and, then in } the opposite direction during the o~her phase of oscillat-on.
Though, by controlling amplitude, flow measurements may be made by direct measurement of distortion, i.e., strobe lighting the base leg 19 at the midpoint of oscillation with, for instance, an analogue scale fixed adjacent to end portions and a pointer carried by base leg 19, a pr~ferred mode of measurement involves determining the time difference between the instance in which the leading and trailing edges of the base leg 19 move through the midpoint plane. This 20 avoids the need to control amplitude. Further, by measuring the up oscillation distortions and the down oscillation distortions in the time measurement mode r anomalies re-~ulting from physical misalignment of "U" shaped conduit 14 relative to the midpoint plane are cancelled rom the measure-ment results.
The essentially conventional - given ~he above dis-cussion of the purposes of the invention - electronic as-pects of the invention will be more readily understood with re~erence to FIGUR~S 5 through 8.
As shown in FIGURE 5, dxive circuit 27 is a simple means for dekecting the signal generated by movement of maynet 25 in sensor coil 23. Deteetor 39 compares the voltage produced by sensor coil 23 with reference voltaye 37. As a result, the gain of force coil amplifier 41 is a function of the velocity of ma~net 25 within sensor coil 23.
Thus, the amplitude of the oseillation of "U" shaped conduit 14 is readily controlled. Sinee "U" shaped conduit 14 and spring arm 22 are permitted to oscillate at their resonant frequeneies, frequency eontrol is not required.
The circuitry of FIGURE 5 provides additional informa-tion. The output of foree eoil amplifier 41 is a sinusoidal signal at the resonant frequency of "U" shaped conduit 14.
Since the resonant frequency is determined by the spriny constant and mass of the oscillating system, and given the fact that the spring constant is fixed and the mass changes only as the density of the fluid flowing through the conduit (the eonduit mass elearly does not change), it will be appreeiated that any ehange in frequeney is a funetion of the ehanye in density of the fluid flowing through the eonduit. Thus, sinee the time period of the oseillation ean be determined, it is a simple matter to count a fixed fre-queney oseillator during the time period to determine a density faetor. Onee generatedl the density faetor can be eonverted to flu1d density by, for instanee, a ehart or graph in that the time period is not a linear funetion of density, but only a determinable funetion thereof. Should a direet readout he desired, a mieroproeessor ean be readily programmed to eonvert the density ~aetor direetly to fluid density.
The nature and funetion of readout eireuit 33 will be - 30 more readily understood with referenee to the logie eireuit illustrated in FIGURE 6, and the related timing diagrams of l ~, 3~
FIGURE 7 and 8. Readout circuit 33 is connected to inlet side sensor 43 and outlet side sensor 44 ~7hich develop signals as flags 45 and 46 carried on base leg 19 pass by the respective sensor at approximately the midpoint of plane A-A the oscillation of "U" shaped conduit 14. As shown, inlet sensor 43 is connected through inverter amplifier 47 and inverter 48 ~hile outlet side sensor 44 is similarly connected through inverter amplifier 4~ and inverter 50.
Line 52, the output from inverter 50, provides, as a result of the double inversion, a posltive signal to the set side of flip-flop 54. Similarly, line 56 provides the output from inverter 48, ayain a positive signal, the reset side of flip-flop 54. Accordingly, flip-flop 54 will be set upon output of a positive signal from sensor 44, and reset on the subsequent output of a positive signal from sensor 43.
In a similar manner, line 58 provides the inverted signal from sensor 43 through inverter amplifier 47 to the set side of flip-flop 60, while line 62 provides the output of inverter amplifier 49 to the reset side of flip-flop 60.
Thus, flip-flop 60 would be set upon the output of a negative signal from sensor 43, and r~set upon the subsequent output of a negative signal from sensor 44. The output of flip-flop 54 is connected through line 63 to a logic gate such as AND gate 64. ~ND gates 64 and 66 are both connected to the output of oscillator 67 and, accordingly, upon output from flip-flop 54, the signal from oscillator 67 is gated through AND gate 64, to line 68 and thus to the downcount side of up-down counter 70. Similarly, upon the output of a signal from flip-flop 60, the output of oscillator 67 is gated through ~ND gate 66 to line 69 connected to the upcount side of updown counter 70.
l~us, in function, readout circuit 33 provid~s a do~,m-count signal at ~he frequency of oscillator 67 to updo~
counter 70 for the period during which sensor 44 is activa-ted prlor to activation of sensor 43 during the down motion of "U" shaped conduit 14, while an upcount signal is provided to up-down counter 70 for the period during which sensor 43 is activated prior to activation of sensor 44 during the up motion of "U" shaped conduit 14.
The significance of readout circuit 33 will be more readily appreciated with referenee to the timing diagram of FIGURE 7 and FIGURE 8. In FIGURE 7, wave forms are illu~
strated ~or the condit~on in which "U" shaped conduit 14 is oscillated in a noflow condition, but in which flags 44 and 46 are not precisely s~atically aligned with plane A-A.
Thus, as shown in the timing diagram, sensor 44 initialLy switches positive early relative to the ideal time repre~ented by the vertical lines on the upstroke, and switches negative late on the down stroke as a result o~ the misalignmen~ o~
flag 46. On the other hand, sensor 43 switches positive late on the upstroke and switches negative early on the downstroke. Eowever, wh~n the outputs rom flip-flops 54 and 60 are analysed and considering further than these fllp-flops provide either downcount or upcount signals respectively to updown counter 70~ it will be seen that flip10p 54, operating on the positive or leading edge o the signals of sensors 43 a~d 44, provid~s an output on the up stroke, while, in view of the unchanged orientation flags 45 and 46, ; flip-flop 60 provides a similar output on the downstroke.
Accordingly, over a complete cycle, the up down counter 70 is first downcoun~ed a finite number of coun~s by the outp-~
of flip-flop 54, thruugh gate 64J and then upcounted an equal l`:
amount by the output of flipflop 60 through gate 66.
; Accordingly, the resulting count in up-down counter 70 is zero, representative of the no-flow condition.
On the other hand, under flow conditions as shown in FIGURE 8, sensor 43 is activated earlier than in FIGURE 7 as a result of the distortion of base leg 19 by the Coriolis force couple resulting from fluid flow, as discussed above.
Similarly, sensor 44 is activated later for an identical reason. Thus, on the upstroke, flip-flop 54 is activated for j 10 a substantially longer period than in the condition of FIGURE 7 since the misalignment of flags 45 and 46 is added to the distortion of base leg 19 by the Coriolis force couple in the up movement. On the other hand, upon down movement, i.e., generating the negative or trailing edge of the signals from sensors 43 and 44, the Coriolis force couple is reversed thus causing sensor 43 to be deactivated ~ earlier and sensor 44 to be deactivated later. Accordingly, ; flip-flop 60 is activated for a diminished period of time.
As is clear from the relative times of activation of the two 1ip-flops, the downcount period of updown counter 70 is substantially longer than the upcount period resulting from activation of flip-flop 60. The resulting increased count in the downcount sid~ of up-down counter 70 is an accurate indication of the flow over a period of oscillation. The count in up-down counter 70 after a given number of oscilla-tions is directly proportional to mass flow in "U" shaped conduit 14 during that time period. The number of oscilla-tions may be determined by, for instance, counting the number of activations of, as a typical example, flip-flop 54 at downcounter 71 connected to the output of flip-flop 54 by line 72. Thus, upon the occurrence of "N" outputs from flip-flop 54, downcounter 71 is activa'ced a~d, in turn, activates logic sequencer 74. Logic sequencer 74 is con-nected to oscillator 67, and at the frequency of oscilla or 67, first latches latch decoder driver 77 through line 78 and then resets updown counter 70 through line 75. Thus until logic sequencer 74 is again activated after "N" out-puts from flip-flop 54, display 80 indicates the accumulated count of up-down counter 70 at the time of interrogation thereof, and accordingly displays mass flow rate for the period of "N" oscillations.
Total mass flow for a selected reset period is similarly provided in that the output from up-down counter 70 is sup-plied to dlgital integrator 82 which is also connected to crystal oscillator 84. Thus the counts from updown counter 70 are integrated with re~ard to time, i.e., the fixed, stable frequency of oscillator 84, and the intergal provided to latch decoder driver 85 which in turn is connected to ~ display 87 to provide a total mass flow readout for the ; period from last activation of reset 88, i~e., a switch connected to digital integrator 82.
As described above, the density factor may also be determined independent of mass flow measurements by activating flip-flop 90 at the clock frequency of the output of flip-flop 54 through line 92. The output of flip-flop 90 is provided to AND gate 94 which, upon activation of flip-flop 90 provides the count of crystal oscillator 84 to counter latch driver 96. Thus, with time information in terms of the counts from crystal oscillator 84l and with the period of oscillation datum from flip-flop 90, available the count in counter latch driver 96 is a function of density of the fluid in "U"
shaped conduit 14, and accordingly, the readout at display 98 provides the density factor discussed above. Since the densit~ factor is not a linear function of the period of oscillation of "U" shaped conduit 14, the readout at display 98 must be further processed, either manually through a graph or through a microprocessor for density or specific gravities per se.
Summarily, it will be recognized that, in the most pre-ferred embodiment of flow meter 10 of the present invention, provides, as desired, instantaneous mass flow rate, cumulative lQ flow rate over any given period, density information as to the fluid, and volumetric flow rate if desired, i.e., by dividiny mass flow rate by density. This is accomplished, accordin~ to empirical tests, at accuracies of 0.1 ox 0.2 percent and will, for instance, measure gas flow at quite low rates in an accurate manner. There is no need to regu-late the amplitude of the frequency of flow meter 10 in the preferred embodiment, i.e., when measuring the time period between output of one sensor until the output of the other sensor.
Another embodiment of the invention is shown in FIGURE
9, whereat mass flow meter 100, which is similar in many respects to flow meter device 10, is illustrated. As shown, flow meter 100 includes a ~ase 102 and "U" shaped conduit 104 extending therefrom in a substantially solidly mounted, i.e., free of pivoting devices, manner. "U" shaped conduit - 104 includes inlet 105 and outlet 106 which communicate with inlet leg 108 and outlet leg 109, respectively. Legs 108 and 109 are arranged to pivot at points 112 and 11~
along axis W'-W' to permit oscillation of "U" shaped conduit 104 around axis W'-W'. This may be facilita~ed by, for ..~L~
instance, a thinniny in the walls of "U" shaped conduit 104 at pivots 112 and 114, but such pivot points are continllous areas of "U" shaped conduit 104 and may be unaltered tubes.
Base leg 116 connects inlet leg 108 and outlet leg 109 thus completing "U" shaped conduit 104.
Contrary to the preferred arrangement of flow meter 10, "U" shaped conduit 104 may advantageously have less resis-tance to bending around -the Coriolis force distortion axis than around oscillation axis W'-W' since Coriolis force 10 distortion is nulled. Magnets 118 carried on base leg 116 by supports 119 interact with drive coil 120 to oscillate "U" shaped conduit 104. Preferably, drive coil 120 is carried on cantilevered spring leaf 122 which is pivotally mounted adjacent axis W'-W' and of a natural frequency substantially equivalent to that of "U" shaped conduit 104 carrying the contemplated fluid therein. Of course, the mounting of magnet 118 and force coil 120 may be reversed, i.e., on conduit 104 and leaf spring 122, respectively.
Also, leaf spring 122 may he dispensed with entirely when base 102 is of substantial mass compared to the mass of "U"
shaped conduit 104 and the fluidized material flowed there~
through. However, in most instances, it is pref~rred to oscillate "U" shaped conduit 104 and leaf spring 122 at a common frequency but 180 out of phase to internally balance the forces within flow m~ter 100 and avoid vibration of base 10~ .
Base leg 116 carries magnets 125 and 126 which depend down-.7ardly therefrom. Magnet 125 is disposed within sense coil 128 mounted to base 102, while magnet 126 is similarly 30 disposed within sense coil 129 also mounted on base 102.
Magnet 125 extends within force coil 131 arranged symmetrically with sense coil 12~, while magnet 126 extends within force ; coil 132 similarly mounted relative to sense coil 129. De-flection sensing means 133 and 134, which are shown in a simplified manner in FIGURE 9, but in more de-tail in FIGU~ES
11 through 13, are positioned adjacent the intersection of inlPt legs 108 and 109 and base leg 116.
Turning now to FIGURE 10 which sets forth the circuit details not shown in FIGURE ~, it should be noted ~hat sense coils 128 and 129 are connected in series in such a manner that the movement of magnets 125 and 126 into sense coils 128 and 129 will generate a sinusoidal signal 'IA" with an amplitude proportional to the velocity of the "U" shaped conduit 104. This signal, the magnitude of which is pro-portional to the speed of movement of magnets 125 and 126, and accordingly a function of the amplitude of oscillation of "U" shaped conduit 104, is provided to AC amplifier 135, and to diode 136 which permits only the positive portion of the sinusoidal signal to charge capacitor 137. Accordingly, the input from diode 136 and capacitor 137 to differential a~plifier 138 is determined by the magnitude of the sinu-soidal signal. Differential amplifier 138 compares such input with reference voltage VRl. Thus, if the voltage of capacitor 137 exceeds VRl, amplifier 138 outpu~s a stronger signal. The output from AC amplifier 135, which i~ of cours~ a sinusoidal signal in phase with the oscillation of 'tU" shaped tube 104 and of a magnitude determined by ~he gain control outputed by differential amplifier 138, drives coil 120 to maintain the desired oscillation of "U" shaped tube 104. Signal A is also supplied to a bridge formed of resistors 140, 141, 142 and photoresistor 143. Resistor 144 i9 included in a feedback loop between resistors 140 and 142, and the output from the interconnection of resistors 140, 142 and 144 is connected to, for instance, the minus input of diffexential amplifier 145. A variable light source, such as LED 147, is connected through resistor 148 to the output of servo amplifier 150. Servo compensator 152 is ~ conventional expedient in servo systems as described in Feedback Control Systems, Analysis And Synthesis, by D'Azo and Hopuis, published by McGraw Hill, 1966, forms the feed-back loop bPtween one input of servo amplifier 150 and the output therefrom. Signal B, which is a DC signal porpor-ti~nal to the small, unnulled distortion of "U" shaped conduit 104 generated as described below with regard to FIGURES 11, 12 and 13, is connected through resistor 153 to an input of servo amplifier 150. The output of servo am-plifier 150 is referenced to voltage VR2 and connected through resistor 148 to LED 147. Thus, as a function of the magnitude of signal B with respect to VR2 driving servo amplifier 150, the intensity of LED 147 is regulated. For instance, the resistivity of photoresistor 143 decreases upon an increase in intensity of LED 147, thereby decreasing the signal supplied to the positive input of differential amplifier 145 relative to that through resistors 140 and 142 to the negative input thereof. Thus, the output of dif-ferential amplifier 145 is 180 out of phase with signal A, since the positive input thereto is decreased while the negative input is not. In summary, as signal B increases, LED 147 is dimmed and photoresistor 14 increases in resis-tivity, this causes the output of differential amplifier 145 in phase with signal A to increase. The output of differen-tial amplifier 145 is connected to force coils 131 and 132 which, as described above, are supported on base 102 and l.
r;~, :
connected in series and out o~ phase. Thus, current throug'n ~; force coils 131 and 132 crea~es, with reference to FIGI~ 9, ,.................. a torque by attracting, for instance, magnet 125 and re-' pelling magnet 126, both of which are connected to base leg . 116~ This torque across base leg 116 nulls distortion of : base leg 116 as a result of Coriolis forces generated by flow through "U" shaped conduit 104.
Resistors 155, 156 or 157 are connectable, by means of switch 159 and, to force coils 131 and 132 thereby providing a selectable load to adjust the scale factor and provide for ~ greater or lesser torque on base leg 116. The output fro~
: series connected force coils 131 and 132 are also connected as one input to synchronous demodulator 162, which will be clescribed in more detail with reference to FIGURE 14. The output of synchronous demodulator 162 is a DC signal propor-tional to mass flow rate, and accordingly provides a measure-ment of mass flow rate. A DC volt meter ~not shown) may be connected to the output of synchronous demodulator 162 to provide a visual reading of mass flow rate through "U"
shaped conduit 104 3 or the DC signal may b directly em-ployed in, for instance, a control loop to other equipment.
As shown in FIGURE 11, deflection censors 133 and 134 may comprise, or instance, left flag 164 and right flag 165 which depend from conduit 10~. Fixed let flag 166 and fixed right flag 167 are mounted on base 102. Accordingly, as base leg 116 oscillates, flags 164 and 165 will preclude light from light svurces 169 and 170 from reaching photosensors 181 and 182, respectivelyO Preferably, the point at which flags 164 and 166, and 165 and 167 intersect to block light is about at the midpoint of oscillation of base leg 116, but one set of flags may be offset somewhat from the other with regard to the interference point. It will be recognized that in the event of distortion of base leg 116 angularly relative to base 102 as a result of Coriolis forces generated by flow through "U" shaped conduit 104, a change in time lapse will exist between the occulting by flags 164 and 166 and flags 165 and 167. The time difference, and sense, will be dependent UpOIl, at a fixed oscillating rate of base leg 116, the Coriolis forces generated and the direction o~ oscillation.
Photosensor 181 is connected to flip-flop 185 at the reset side and 186 at the reset side, with the connection to flip-flop 186 being through inverter 188. Differentia~ing capaci-tors 191 and 192 are included in reset input. Similarly, photosensor 182 is connected to ~he set side of flip-flop 185 and, through inverter 189 to the set sid~ of flip-flop 186 with differentiating capacitors 193 and 194 similarly included in the inputs. Thus, as flags 164 and 166 close, a positive signal is generated by photosensor 181 which acti-vates the rese~ side of flip flop 185 and as flags 165 and 167 clo~e, a positive signal is similarly generated by photosensor 182 to aetîvate the set side of 1ip-flop 185.
Accordingly, flipflop 185 is activated for the period be-tween the closing of such sets of flags. On the other hand, the opening of flags 164 and 166, and 165 and 167, generates a falling edge, or negative signal, from photosensors 181 ~nd 182, respectively, which similarly activate flip-flop 186 through inverters 188 and 189. Accordingly, flip~flop 186 is activated for the period between the opening of one set of such flags and the other set. The outputs from flip-flop 185 and 186 are provided, through resistors 195 and 196, respectively, to the inputs of differential integrator 198. Integrating capacitor 200 is provided in associatlon with resistor 195, while integrating capacitor 201 is pro-vided in association with resistor 196 at such inputs to provide integrating capaci~y.
Ou~put signal B from di~ferential integrator 198 thus depends on the periods of activation of flip-flops 185 and 186. In the event that base leg 116 is merely oscillating without distortion, the time differences between the opening and closing of ~he flags wlll be substantially constant and the inputs to differential integrator 198 essentially identi-cal, thereby providing no signal B. On the other hand, inthe event Coriolis forces are generated, base leg 115 will be distorted in a clockwise direction on one stroke of the oscillation, and in a counter clockwise direction on the other stroke. Thus, the closing on one side of the flags will be early on one stroke and late on the other, while th~
other set of flags will be late on the firs~ stroke and early on the other. The activation of flipflops 185 and 186 therefore will not be for equal lengths of ~ime, and differ-~ntial integrator 198 will output an appropriate DC signal B
of a desired plus or minus sense depending upon the phase of the distortion of base leg 116 relative to the up/down stroke.
Another arrange~ent to provide the same result is shown i~ FIGUP~ 12. As shown, strain gages 204 and 205 are moun~ed adjacent the intersection of inlet leg 108 and base leg 116, and ouklet leg 109 and base leg 116, respectively. Strain gages 204 and 205, which may be viewed as variable resistors dependent upon the distor~ion of the adjacent portion of "U"
shaped condui~s 104, are connected with resis~ors 207 and 208 to form a bridge circuit communicating with a voltage sour~e as indicated, and connected to AC differential ampli-i,:
fi r 210. In the case of simple oscilla~ion of "U" shaped ~ conduit 104, the resistivfity of strain gages 204 and 205 ;~ vary equally thereby providlng essentially identical inputs to AC differential amplifier 210. However, in the event of distortion due to Coriolis forces, one of strain gages 204 and 205 will increase in resistivity while the other de-.:
creases thereby providing different inputs to AC differen-tial amplifier 210 and providing an output in the form of an AC signal proportional in magnitude and sense to the dif-10 ferent strains imposed upon strain gages 204 and 205.
The output from AC differential amplifier 210 is pro-vided to synchronous demodulator 211, which, in conjunction with signal A, provides a DC output propor~ional in mag-nitude and sense to the distortion of "U" shaped conduit 104 as a result of Coriolis forces. Synchronous demodulator 211 is similar to above~described synchronous demodulator 162, which will be described in more detail wi~h reference to ;~ FIGURE 14.
: A somewhat similar arrangemen~ for generating signal B
is illustrated in FIGURE 13. In this instance, however, pivot member 215 is mounted centrally on base leg 116 and carries inertia bar 217 which is free ~o rotate around pivot ~! member 215 and balanced thereon. Crystals 219 and 220 are connected between inertia bar 217 and ba~e leg 116. Thus, if base leg 116 undergoes simple oscillation, inertia bar 217 merely follows the o~cillation without a tendency to rotate around pivot member 215. How~ver, in the event of distortion of "U" shaped conduit 104 as a resul~ of Coriolis forces, base leg 116 tends to rotate relative to inertia bar 217, thereby imposing forces in opposite directions upon ; crystal 219 and 220 and thus generating, as a result of
-2~-piezoelectric effect, signals from crystals 219 and 220.
The outputs from erystals 219 and 220 are connected to AC
differential amplifier 222, which in turn is connected to synchronous demodulator 224 to provide, in conjunction with signal A, a DC signal B of a magnitude and sense proportional to the distortion of "U" shaped eonduit 104. It is to be understood, of eourse, that a voltage source and strain gages eould be eonveniently employed in place of crystals 219 and 220.
Synehronous demodulator 162, deseribed above with reference to FIGURE 10, and accordingly, similar to synchronous demodulators 211 and 224, is deseribed in more detail at FIGURE 14. As shown, input signal in the form of an AC sig-nal is provided at input line 225 to the primary winding 227 of a transformer. Seeondary windings 228, having a common ground, are, as indieated by the polarity, wound in opposi~e directions. Thus, the output from the opposed ends of seeondary windings 228 will be out of phase by 180. Switeh-ing meansr in the form of FET transistors 230 and 2.31 are provided in the outputs from seeondary windings 228. Compara-tor 233, whieh is eonneeted to signal A, outputs positive or negative signals depending upon the relationship of signal A
to referenee voltage VR3. ~he output of eomparator 233 thus is a square wave signal of positiv~ or negative sense, and is provided to inverter 235 whieh inverts the signal. Thus, one portion of the square wave signal turns on switehing means 230 while switehing means 231 is turned off, and the other portion turns on switehing means 231 while switehing means 230 is of. Aeeordingly, the portion of input signal 225 whieh is in phase with signal A is provided to RC eireuit 237 formed of resistor 238 and eapaeitor 239 whieh outputs L~
,:
a DC signal which is propvrtional to the root mean square of , the input to filter 237. This DC output consti~utes the -readout as described above, i.e., 2 DC signal proportional to the mass flow through "U" shaped conduit 104.
In summary, flow meter 100 described above, utilizes deflection sensors 133 and 134 to detect the magnitude and . sense of small, incipien~ deflections of "U" shaped conduit 104 due to Coriolis force and generate a DC signal of a sense and magnitude proportional to such deflection. The DC
10 signal, signal B, ls in essence a feedback 3ignal which regulates the nulling force generated by force coils 131 and 132 to produce a counterforce thus preventing appreciable distortion beyond the incipient sensed distortion. Sense coils 128 and 129, in addition to maintaining the frequency of oscillation of "U" shaped conduit 10~ through the drive circuit described above3 also provides signal ~, a signal in phase with the Coriolis forces thus providing for proper modulation o~ force coils 131 and 132, proper synchroniz~tion of the output of AC amplifier 135 to drive "U" shaped conduit s 20 104 and proper de~odulation of the synchronous signal of force coil9 131 and 132 to produce a DC output proportional to mas s f low rate .
Though the two generally preferred means for measuring the Coriolis forces are described in detail above, i.e., allowing resilient deflection o~ the conduit and measuring the de1ection, or nulling the force to preclude deflection and measuring the nulling force, numerous other generally less desirable means exist. In any event, by uslng a solidly mounted "Ui' shaped conduit essentlally free of pressure 30 sensitive joints or pivot means, oscillation and deflection may be readily accomplished and mass flow determined over wide pressure ranges.
Although only limited preferred embodiments of the invention have been illustrated and described, it is anti-cipated that various changes and modifications will be apparent to those skilled in the art, and that such changes may be made without departing from the scope of the inven-tion as defined by the following claims.
The outputs from erystals 219 and 220 are connected to AC
differential amplifier 222, which in turn is connected to synchronous demodulator 224 to provide, in conjunction with signal A, a DC signal B of a magnitude and sense proportional to the distortion of "U" shaped eonduit 104. It is to be understood, of eourse, that a voltage source and strain gages eould be eonveniently employed in place of crystals 219 and 220.
Synehronous demodulator 162, deseribed above with reference to FIGURE 10, and accordingly, similar to synchronous demodulators 211 and 224, is deseribed in more detail at FIGURE 14. As shown, input signal in the form of an AC sig-nal is provided at input line 225 to the primary winding 227 of a transformer. Seeondary windings 228, having a common ground, are, as indieated by the polarity, wound in opposi~e directions. Thus, the output from the opposed ends of seeondary windings 228 will be out of phase by 180. Switeh-ing meansr in the form of FET transistors 230 and 2.31 are provided in the outputs from seeondary windings 228. Compara-tor 233, whieh is eonneeted to signal A, outputs positive or negative signals depending upon the relationship of signal A
to referenee voltage VR3. ~he output of eomparator 233 thus is a square wave signal of positiv~ or negative sense, and is provided to inverter 235 whieh inverts the signal. Thus, one portion of the square wave signal turns on switehing means 230 while switehing means 231 is turned off, and the other portion turns on switehing means 231 while switehing means 230 is of. Aeeordingly, the portion of input signal 225 whieh is in phase with signal A is provided to RC eireuit 237 formed of resistor 238 and eapaeitor 239 whieh outputs L~
,:
a DC signal which is propvrtional to the root mean square of , the input to filter 237. This DC output consti~utes the -readout as described above, i.e., 2 DC signal proportional to the mass flow through "U" shaped conduit 104.
In summary, flow meter 100 described above, utilizes deflection sensors 133 and 134 to detect the magnitude and . sense of small, incipien~ deflections of "U" shaped conduit 104 due to Coriolis force and generate a DC signal of a sense and magnitude proportional to such deflection. The DC
10 signal, signal B, ls in essence a feedback 3ignal which regulates the nulling force generated by force coils 131 and 132 to produce a counterforce thus preventing appreciable distortion beyond the incipient sensed distortion. Sense coils 128 and 129, in addition to maintaining the frequency of oscillation of "U" shaped conduit 10~ through the drive circuit described above3 also provides signal ~, a signal in phase with the Coriolis forces thus providing for proper modulation o~ force coils 131 and 132, proper synchroniz~tion of the output of AC amplifier 135 to drive "U" shaped conduit s 20 104 and proper de~odulation of the synchronous signal of force coil9 131 and 132 to produce a DC output proportional to mas s f low rate .
Though the two generally preferred means for measuring the Coriolis forces are described in detail above, i.e., allowing resilient deflection o~ the conduit and measuring the de1ection, or nulling the force to preclude deflection and measuring the nulling force, numerous other generally less desirable means exist. In any event, by uslng a solidly mounted "Ui' shaped conduit essentlally free of pressure 30 sensitive joints or pivot means, oscillation and deflection may be readily accomplished and mass flow determined over wide pressure ranges.
Although only limited preferred embodiments of the invention have been illustrated and described, it is anti-cipated that various changes and modifications will be apparent to those skilled in the art, and that such changes may be made without departing from the scope of the inven-tion as defined by the following claims.
Claims (29)
1. A flow meter for flowable materials comprising:
a support;
a "U" shaped, continuous conduit solidly mounted at the open end of the "U" to the support and extending therefrom in a nonarticulated, cantilevered fashion;
a driver for oscillating the conduit relative to the support on either side of the static plane of the "U" shaped conduit and about a first oscillation axis; and a sensor to measure the Coriolis forces tending to elastically distort the "U" shaped conduit around a second deflection axis positioned substantially equidistant between the side legs of the "U" shaped conduit and through the oscillation axis thereof.
a support;
a "U" shaped, continuous conduit solidly mounted at the open end of the "U" to the support and extending therefrom in a nonarticulated, cantilevered fashion;
a driver for oscillating the conduit relative to the support on either side of the static plane of the "U" shaped conduit and about a first oscillation axis; and a sensor to measure the Coriolis forces tending to elastically distort the "U" shaped conduit around a second deflection axis positioned substantially equidistant between the side legs of the "U" shaped conduit and through the oscillation axis thereof.
2. The flow meter as set forth in Claim 1 in which the sensor to measure Coriolis forces comprise a detecting device to measure the angular deflection of the "U" shaped conduit as a result of elastic deformation of the "U" shaped conduit around the second deflection axis positioned substantially equidistant between the conduit side legs.
3. The flow meter as set forth in any of Claims 1 or 2 in which the resonant frequency of the "U" shaped conduit a-round the first oscillation axis is lower than the resonant frequency of the "U" shaped conduit around the second deflec-tion axis.
4. The flow member as set forth in Claim 1 in which the driver for oscillating the conduit comprise a magnet mounted on the "U" shaped conduit, a sensor coil mounted adjacent the magnet, a force coil mounted adjacent the magnet, and a power source to supply an electrical cur-rent to the force coil in response to a signal determined by moving the magnet past the sensor coil.
5. The flow meter as set forth in Claim 4 in which the driver further comprise a detector to identify the peak amplitude of the signal generated by the sensor coil as a result of relative movement between the sensor coil and the magnet and to output current to the force coil such that a preselected amplitude of oscillation is maintained.
6. The flow meter as set forth in Claim 1 in which the "U" shaped conduit has attached thereto at the oscillation axis a spring arm having a natural resonant frequency substantially that of the "U" shaped conduit.
7. The flow meter as set forth in Claim 6 in which a sensor coil and force coil are carried on the spring arm or the conduit, and a magnet positioned adjacent both the sensor coil and force coil is carried on the other of the spring arm or conduit, with the magnet, sensor coil and force coil in conjunction with an amplifier and peak detector comprising the driver for oscillating the conduit around the first oscillation axis.
8. The flow meter as set forth in Claim 1 in which first and second sensors are mounted adjacent the "U" shaped conduit at symmetrical positions rela-tive to the second deflection axis and substantially at the mid-point of oscillation of the conduit, each sensor being adapted to output a signal as the adjacent portion of the "U" shaped conduit passes through the mid-plane of oscil-lation, and further including a timer for measuring the time lag between signal outputs by the sensors thereby establish-ing the degree of deflection of the "U" shaped conduit.
9. The flow meter as set forth in Claim 8 in which a timer subtracts the time lags in one direction of oscillation from that of the other direction of oscillation.
10. The flow meter as set forth in Claim 8 in which the output from the first and second sensors are each electrically connected to a pair of inverters in series, the outputs of the first inverters in each series being connected one each to the set and reset inputs of a first flip-flop and the outputs of the second inverters in each series being con-nected one each to the set and reset inputs of a second flip-flop, first and second logic gates, the output from the first flip-flop being connected to an input of the first logic gate and the output of the second flip-flop being connected to an input of the second logic gate, an oscillator connected to inputs of both the first and second logic gates, the output of the first logic gate being connected to one clock input of an up-down counter, and the output of the second logic gate being connected to the other input of the up-down counter.
11. The flow meter as set forth in Claim 10 further including a readout for transferring and displaying the output from the up-down counter to a display register upon the occurrence of "N" oscillations of the "U" shaped conduit as a readout of the mass flow therethrough and also includ-ing a signal generator for resetting the up-down counter after transfer to the up-down counter output to the display register.
12. The flow meter as set forth in Claim 10 further in-cluding a fixed frequency oscillator and in which the output of the updown counter is connected to a digital integrator, the digital integrator also being connected to the output of the fixed frequency oscillator, the integrated output of the integrator being connected to a display readout of total mass flow, and further including a signal generator for resetting, latching and displaying the output from the digi-tal integrator upon the occurrence of the "N" oscillations of the conduit.
13. The flow meter as set forth in Claim 2 including a frequency counter for measuring the time period of oscillation of the "U" shaped conduit and displaying the time period as a related function of the density of a fluid flowing through the "U" shaped conduit.
14. A flow meter as set forth in Claim 1 in which the sensor to measure Coriolis forces comprise:
a detector to sense distortion of the "U" shaped conduit around the second deflection axis positioned substantially equidistant between the side legs of the "U" shaped conduit;
a torque generating circuit responsive to the distortion detector to generate a counter force to limit the distortion to but a small, incipient distortion; and a measuring device to determine the counter force.
a detector to sense distortion of the "U" shaped conduit around the second deflection axis positioned substantially equidistant between the side legs of the "U" shaped conduit;
a torque generating circuit responsive to the distortion detector to generate a counter force to limit the distortion to but a small, incipient distortion; and a measuring device to determine the counter force.
15. The flow meter as set forth in Claim 14 in which the detector to sense distortion of the "U" shaped conduit around the second deflection axis comprise centerline crossing sensors positioned one each adjacent the side legs of the "U" shaped conduit at substantially the mid-point of the oscillation around the first oscillation axis.
16. The flow meter as set forth in Claim 15 in which the centerline crossing sensors each comprise a pair of flags, one fixedly mounted and the other attached to the side leg of the "U" shaped conduit and adapted to overlap the fixed flag at about the midpoint of the oscillation, a light source mounted on one side of the flags, and a photosensitive detector mounted on the other side of the flags whereby the centerline crossing may be detected by blocking the light source from the photosensitive detector by the flags.
17. The flow meter as set forth in Claim 14 in which the detector to sense distortion of the "U" shaped conduit comprise a pair of strain gages attached one each to the "U" shaped conduit adjacent each intersection of the side legs and base leg of the "U" shaped conduit, the strain gages forming a bridge circuit having a signal output proportional to the distortion of the "U" shaped conduit around the second deflection axis.
18. The flow meter as set forth in Claim 14 in which the detector to sense distortion of the "U" shaped conduit comprise an inertia bar symmetrically and pivotally mounted at about the mid-point of the base leg of the "U"
shaped conduit, and a pair of force sensors connected one each between each end of the inertia bar and the adjacent portions of the base leg of the "U" shaped conduit.
shaped conduit, and a pair of force sensors connected one each between each end of the inertia bar and the adjacent portions of the base leg of the "U" shaped conduit.
19. A method for measuring mass flow of a material, comprising:
flowing the material through a continuous, joint-free "U" shaped conduit with the inlet and outlet portions thereof solidly mounted in a cantilevered, beam-like fashion to a support;
oscillating the conduit substantially around an axis transverse to the inlet and outlet portions thereof;
generating Coriolis forces in the curved conduit as a result of material flow through the oscillating conduit; and measuring the Coriolis forces tending to deform the conduit around an axis of symmetry substantially perpendicu-lar to the oscillation axis of the conduit.
flowing the material through a continuous, joint-free "U" shaped conduit with the inlet and outlet portions thereof solidly mounted in a cantilevered, beam-like fashion to a support;
oscillating the conduit substantially around an axis transverse to the inlet and outlet portions thereof;
generating Coriolis forces in the curved conduit as a result of material flow through the oscillating conduit; and measuring the Coriolis forces tending to deform the conduit around an axis of symmetry substantially perpendicu-lar to the oscillation axis of the conduit.
20. The method for measuring mass flow as set forth in Claim 19 in which the deforming forces are measured by elasti-cally deforming the conduit around the axis of symmetry thereof substantially perpendicular to the oscillation axis of the conduit; and measuring the angular deflection of the conduit around the axis of symmetry as an indication of the Coriolis forces.
21. The method for measuring mass flow as set forth in Claim 20 in which the angle of deflection is determined by measuring the time differential between passage of one por-tion of the conduit through a plane including the oscillation axis, axis of symmetry and substantially at the midpoint of the oscillation, and the passage of a second portion of the conduit through such plane.
22. The method for measuring mass flow as set forth in any of Claims 19, 20 or 21 in which the conduit is oscillated at the resonant frequency of the conduit and material therein.
23. The method for measuring mass flow as set forth in Claim 19 in which the deforming forces are measured by sensing incipient distortion of the conduit around the axis of symmetry substantially perpendicular to the oscillation axis of the conduit;
generating a force opposing the deforming forces in response to the sensed incipient distortion; and measuring the opposing force to determine mass flow.
generating a force opposing the deforming forces in response to the sensed incipient distortion; and measuring the opposing force to determine mass flow.
24. The method for measuring mass flow as set forth in Claim 19 in which a spring arm having a resonant fre-quency substantially identical to that of the conduit is attached to the conduit adjacent the inlet and outlet portions thereof and oscillated out of phase with con-duit.
25. The method for measuring mass flow as set forth in Claim 24 in which the conduit and spring are are oscillated by generating a force between a magnet mounted on one of the conduit and spring arm and a force coil mounted on the other of the conduit and spring arm.
26. The method for measuring mass flow as set forth in Claim 23 in which the incipient distortion is detected by measuring the time differential between passage of one portion of the conduit through a plane at the midpoint of the oscillation and the passage of a second portion of conduit through such plane.
27. The method for measuring mass flow as set forth in Claim 23 in which the incipient distortion is detected by strain gages mounted on the conduit at positions symmetrical relative to the axis of symmetry.
28. The method for measuring mass flow as set forth in Claim 23 in which the incipient distortion of the conduit is detected by crystals mounted between the conduit and an inertia bar pivotally mounted to the conduit at the axis of symmetry, the crystals being positioned symmetrically rela-tive to the axis of symmetry of the conduit.
29. The method for measuring mass flow as set forth in Claim 19 in which the conduit is oscillated at a predetermined amplitude.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US81847577A | 1977-07-25 | 1977-07-25 | |
| US818,475 | 1977-07-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1106636A true CA1106636A (en) | 1981-08-11 |
Family
ID=25225627
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA307,980A Expired CA1106636A (en) | 1977-07-25 | 1978-07-24 | Method and structure for flow measurement |
| CA000488475A Expired CA1210611B (en) | 1977-07-25 | 1985-08-09 | Method and structure for flow measurement |
Family Applications After (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000488475A Expired CA1210611B (en) | 1977-07-25 | 1985-08-09 | Method and structure for flow measurement |
Country Status (17)
| Country | Link |
|---|---|
| JP (1) | JPS6034683B2 (en) |
| AU (1) | AU512637B2 (en) |
| BE (1) | BE869206A (en) |
| CA (2) | CA1106636A (en) |
| CH (1) | CH641277A5 (en) |
| DE (1) | DE2833037A1 (en) |
| ES (1) | ES471982A1 (en) |
| FR (1) | FR2399007A1 (en) |
| GB (1) | GB2001759B (en) |
| HK (1) | HK59684A (en) |
| IL (1) | IL55212A (en) |
| IT (1) | IT1106095B (en) |
| MX (1) | MX145013A (en) |
| NL (1) | NL187033C (en) |
| SE (1) | SE447161C (en) |
| SG (1) | SG29384G (en) |
| ZA (1) | ZA784189B (en) |
Families Citing this family (34)
| Publication number | Priority date | Publication date | Assignee | Title |
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| US4252028A (en) * | 1979-02-26 | 1981-02-24 | S & F Associates | Method and apparatus for measuring flow |
| ZA82345B (en) * | 1981-02-17 | 1983-02-23 | J Smith | Method and apparatus for mass flow measurement |
| JPS5838837A (en) * | 1981-08-31 | 1983-03-07 | Toray Ind Inc | Capillary viscometer |
| JPS5885000U (en) * | 1981-10-05 | 1983-06-09 | 東レ株式会社 | Constant weight liquid filling equipment |
| GB2127533B (en) * | 1982-09-30 | 1986-04-23 | Cornelius Co | Filling compressed gas bottles |
| JPH0438261Y2 (en) * | 1986-09-16 | 1992-09-08 | ||
| US4777833A (en) * | 1986-11-12 | 1988-10-18 | Micro Motion, Inc. | Ferromagnetic drive and velocity sensors for a coriolis mass flow rate meter |
| US4914956A (en) * | 1987-07-22 | 1990-04-10 | Exac Corporation | Method and circuit for processing sensory input signals of the type obtained from coriolis mass flow rate sensors and the like |
| DE4016907C3 (en) * | 1990-05-25 | 1998-06-10 | Krohne Ag | Mass flow meter |
| EP0469448A1 (en) * | 1990-07-28 | 1992-02-05 | KROHNE MESSTECHNIK MASSAMETRON GmbH & Co. KG | Mass flow meter |
| DE4124296A1 (en) * | 1990-07-28 | 1992-02-06 | Krohne Messtechnik Massametron | Mass flow measurement arrangement with vibration generator |
| DE4027936A1 (en) * | 1990-09-04 | 1992-03-05 | Rota Yokogawa Gmbh & Co Kg | MASS DISPENSER |
| DE4124295A1 (en) | 1991-07-22 | 1993-01-28 | Krohne Ag | MASS FLOW MEASURING DEVICE |
| HU215043B (en) * | 1992-04-24 | 1998-10-28 | MMG Automatika Művek Rt. | Coriolis type apparatus for measuring mass flow of a fluid stream |
| US5323658A (en) * | 1992-06-19 | 1994-06-28 | Fuji Electric Co., Ltd. | Coriolis mass flowmeter |
| DE4224379C2 (en) | 1992-07-06 | 1998-05-20 | Krohne Messtechnik Kg | Mass flow meter |
| DE4311694C1 (en) * | 1993-04-08 | 1994-09-29 | Fritz Giebler Gmbh | Flow meter |
| DE4423168C2 (en) | 1994-07-04 | 1998-09-24 | Krohne Ag | Mass flow meter |
| DE4435809A1 (en) | 1994-10-07 | 1996-04-11 | Krohne Messtechnik Kg | Measuring device for flowing media |
| WO2001053781A1 (en) * | 2000-01-24 | 2001-07-26 | Micro Motion, Inc. | System for preventing tampering with a signal conditioner remote from a host system |
| US6776053B2 (en) * | 2001-11-26 | 2004-08-17 | Emerson Electric, Inc. | Flowmeter for the precision measurement of an ultra-pure material flow |
| US7127815B2 (en) * | 2001-11-26 | 2006-10-31 | Emerson Electric Co. | Method of manufacturing a Coriolis flowmeter |
| DE102008037700A1 (en) | 2008-08-14 | 2010-02-18 | Endress + Hauser Flowtec Ag | Vibration-type transducers |
| US9341059B2 (en) | 2009-04-15 | 2016-05-17 | Schlumberger Technology Corporation | Microfluidic oscillating tube densitometer for downhole applications |
| CA2760859C (en) * | 2009-05-11 | 2016-09-27 | Micro Motion, Inc. | A flow meter including a balanced reference member |
| AU2009349706B2 (en) | 2009-06-30 | 2013-08-22 | Micro Motion, Inc. | A method and apparatus for separating a driver and a pick-off of a vibrating sensor assembly |
| AU2013203999B9 (en) * | 2009-06-30 | 2014-03-06 | Micro Motion, Inc. | A method and apparatus for separating a driver and a pick-off of a vibrating sensor assembly |
| EP3129755B1 (en) | 2014-04-07 | 2022-07-20 | Micro Motion, Inc. | Improved vibrating flowmeter and related methods |
| KR102212368B1 (en) * | 2015-04-14 | 2021-02-04 | 마이크로 모우션, 인코포레이티드 | How to detect inaccurate flow measurement by vibrometer |
| CN108603779B (en) * | 2016-02-09 | 2021-12-28 | 高准公司 | Method and apparatus for modulating a flow path |
| CN108700904B (en) * | 2016-02-26 | 2020-12-11 | 高准公司 | Limiting current drawn by two or more meter assemblies |
| JP6178033B1 (en) * | 2017-04-03 | 2017-08-09 | 株式会社アツデン | Coriolis mass flow meter |
| DE102019105736B3 (en) * | 2019-03-07 | 2020-06-25 | Endress+Hauser Flowtec Ag | Coriolis sensor and Coriolis measuring device with Coriolis sensor |
| MX2021010883A (en) * | 2019-04-03 | 2021-10-22 | Micro Motion Inc | Determining a vapor pressure using a vapor pressure meter factor. |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2865201A (en) * | 1954-08-26 | 1958-12-23 | Roth Wilfred | Gyroscopic mass flowmeter |
| GB1052644A (en) * | 1963-08-12 | |||
| US3485098A (en) * | 1964-09-03 | 1969-12-23 | Anatole J Sipin | Mass flow metering means |
| US3355944A (en) * | 1964-09-03 | 1967-12-05 | Anatole J Sipin | Mass flow metering means |
| US3449940A (en) * | 1966-07-22 | 1969-06-17 | Automation Prod | Apparatus for measuring physical properties of materials |
| FR1567913A (en) * | 1967-10-09 | 1969-05-23 | ||
| US4127028A (en) * | 1977-06-07 | 1978-11-28 | Halliburton Company | Coriolis mass flow rate metering means |
-
1978
- 1978-07-24 FR FR7821839A patent/FR2399007A1/en active Granted
- 1978-07-24 NL NLAANVRAGE7807846,A patent/NL187033C/en not_active IP Right Cessation
- 1978-07-24 MX MX174279A patent/MX145013A/en unknown
- 1978-07-24 CA CA307,980A patent/CA1106636A/en not_active Expired
- 1978-07-24 ES ES471982A patent/ES471982A1/en not_active Expired
- 1978-07-24 BE BE189448A patent/BE869206A/en not_active IP Right Cessation
- 1978-07-24 ZA ZA00784189A patent/ZA784189B/en unknown
- 1978-07-24 SE SE7808094A patent/SE447161C/en not_active IP Right Cessation
- 1978-07-24 IL IL55212A patent/IL55212A/en active IP Right Grant
- 1978-07-25 CH CH801678A patent/CH641277A5/en not_active IP Right Cessation
- 1978-07-25 GB GB787831007A patent/GB2001759B/en not_active Expired
- 1978-07-25 AU AU38315/78A patent/AU512637B2/en not_active Expired
- 1978-07-25 JP JP53090048A patent/JPS6034683B2/en not_active Expired
- 1978-07-25 DE DE19782833037 patent/DE2833037A1/en active Granted
- 1978-07-25 IT IT50465/78A patent/IT1106095B/en active
-
1984
- 1984-04-09 SG SG293/84A patent/SG29384G/en unknown
- 1984-08-02 HK HK596/84A patent/HK59684A/en not_active IP Right Cessation
-
1985
- 1985-08-09 CA CA000488475A patent/CA1210611B/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB2001759B (en) | 1982-02-10 |
| DE2833037C2 (en) | 1987-01-15 |
| IL55212A0 (en) | 1978-09-29 |
| AU512637B2 (en) | 1980-10-23 |
| NL187033C (en) | 1991-05-01 |
| HK59684A (en) | 1984-08-10 |
| ES471982A1 (en) | 1979-02-16 |
| NL7807846A (en) | 1979-01-29 |
| AU3831578A (en) | 1980-03-20 |
| SE447161B (en) | 1986-10-27 |
| FR2399007A1 (en) | 1979-02-23 |
| GB2001759A (en) | 1979-02-07 |
| SE7808094L (en) | 1979-01-26 |
| CH641277A5 (en) | 1984-02-15 |
| DE2833037A1 (en) | 1979-02-08 |
| JPS5452570A (en) | 1979-04-25 |
| ZA784189B (en) | 1979-07-25 |
| IL55212A (en) | 1984-04-30 |
| JPS6034683B2 (en) | 1985-08-10 |
| MX145013A (en) | 1981-12-14 |
| NL187033B (en) | 1990-12-03 |
| IT1106095B (en) | 1985-11-11 |
| SG29384G (en) | 1985-02-15 |
| FR2399007B1 (en) | 1985-03-29 |
| CA1210611B (en) | 1986-09-02 |
| IT7850465A0 (en) | 1978-07-25 |
| BE869206A (en) | 1978-11-16 |
| SE447161C (en) | 1990-09-10 |
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