CN1066819C - Coriolis flowmeter with stationary coil - Google Patents

Abstract

A coriolis flowmeter having a pair of parallel vibrating flow tubes with a driver and pickoffs mounted on the tubes, each pickoff including a fixed non-moving coil and a pair of magnets secured to the vibrating flow tubes. Each coil is magnetically engaged with a unique pair of magnets. In a first embodiment, the coil is fixed to a non-moving part of the flow meter. In another embodiment, the inactive coils are secured only to the elastomeric subassembly, which is secured to the flow tubes that vibrate out of phase with respect to each other.

Description

Coriolis flowmeter with stationary coil

Background of invention

The present invention relates to a kind of mass flowmeter (hereinafter being sometimes referred to as coriolis mass flowmeters or coriolis flowmeter) with Coriolis effect, relate in particular to that a kind of to have a cost low, the better sensor of good reliability and performance by and the mass flowmeter of the Coriolis effect of drive unit.

Existing problem.

Mass flow meter measurement mass rate and other information through the mobile material of pipeline with Coriolis effect are well-known.As 4,491, No. 025 United States Patent (USP) (authorized people such as J.E.Smith on January 1st, 1985 and authorize the Re 31,450 of J.E.Smith February 11 nineteen eighty-two) put down in writing like that, these flowmeters have the one or more straight or crooked flowtube that is configured to.In coriolis mass flowmeters, every kind of flowtube structure all has one group of eigentone, and the flowtube structure can be simple bending, distortion or conjugated type (coupled type).Drive each flow duct and on a resonance frequency of these natural modes, produce vibration.Material flows into flowmeter from the connecting line of flowmeter entrance side, directly passes flowtube or some pipes, and flows out flowmeter by outlet side.The eigentone of the system vibration of splendid attire fluid is partly limited together by the quality and the material in the flowtube of flowtube.

When not flowing through flowmeter, the driving force in phase vibration of the have a few of longshore current buret because of applying.When material begins to flow, because Coriolis acceleration makes each point of longshore current buret all have different phase places.In driver, and be ahead of driver in the phase lag of flowtube entrance side in the phase place of outlet side.Sensor is arranged on the flowtube to produce the sinusoidal signal of representing the flowtube motion.Phase differential between two sensor signals is directly proportional with the mass velocity that material passes flowtube.

WO 88/03642 has put down in writing a kind of coriolis mass flowmeters, and it comprises a ferromagnetic driving mechanism and some ferromagnetic rate sensors.Driving mechanism comprises a drive coil; A ferromagnetic driving armature that is fixed to the flowmeter traffic channel is so that traffic channel is positioned partially in the field of drive coil a magnet that drives the ferromagnetic magnetic domain orientation of armature with guiding; With the device that is used for providing drive signal to drive coil.Rate sensor comprises a cell winding; A ferromagnetic sensor armature that is fixed to traffic channel is so that its part is arranged in the field of crossing cell winding; A magnet that is used for the ferromagnetic magnetic domain orientation of guiding sensor armature is provided with this magnet and makes the part in its magnetic field pass cell winding; With the electric current that in cell winding, induces by the position probing that changes sensing armature.The variable magnetic field vibrating flow pipeline that driving mechanism response drive signal produces.Because the side branch of flow pipeline response driving mechanism and response are vibrated by the Coriolis force of giving birth to by the material miscarriage of vibration pipeline, ferromagnetic sensor armature position is changed.Changes of magnetic field and induction that the result passes cell winding produce a signal, and this signal is the measurement to the flow velocity of the side branch on flowtube road.

Can produce a problem with the coil connecting line on the pipe that moves.A kind of processing of two kinds of methods of this a kind of usefulness.On bigger flowmeter, pipe near supporting baffle a bit begin insulated wire is attached on the pipe with adhesive tape, near zero, extend up to coil along pipe at the amplitude of this point pipe then.The shortcoming of this method is that adhesive tape or glue and insulated wire are generally high damping material, and they are uncertain about the vibration damping variation of time and temperature.The flow signal that the variation of coriolis flowmeter pipe vibration damping can lead to errors.

On smaller flowmeter, it is bigger that the error that vibration damping causes becomes, to allow to use general lead, therefore, the arc connection of the end points on thin flexible conductor (flexible) forms from the stationary end to the movable coil.Owing to do not have insulated wire or adhesive tape on these flexible conductors, so their vibration damping is very little.Unfortunately, these flexible conductors have strict separately natural frequency, and encourage them can cause rapid failure on a natural frequency.Also have, their size and frangibility make makes difficulty.

The invention solves the problem that is produced to the movable coil line, the present invention is being provided with a magnet and a stationary coil is being set near two magnets on each pipe.Magnet is orientated like this, promptly each of these magnets with the identical utmost point towards coil and make these pipes about each other the motion (out-of-phase motion), they radially cross coil and produce auxiliary voltage in coils.Adopt this geometry, the simultaneous movements of pipe causes a magnet to cross coil towards hub of a spool, crosses coil and another magnet leaves hub of a spool.The voltage that is produced by this motion subtracts each other each other and offsets.The same simultaneous movements that leaches flowtube of this new geometry with prior art, but less than the problem to the movable coil line.

The amplitude of the sinusoidal signal that produces by the coil of the present invention design with and the intensity in the crossing magnetic field of coil be directly proportional.Because field intensity reduces with the distance of leaving magnet, so, keep this distance be constant in time just becoming very important, particularly carry out under electric signal handles with the situation of determining Δ t using a kind of (non-zero) voltage levvl to intersect to measure.Be difficult to keep that this distance (at interval) is constant to realize making the magnet straight line forward near pipe with make coil near flowmeter shell, this is because flowtube and housing generally are fixed to one another at flowmeter concetrated pipe place and leave magnet and the tangible distance of coil.Like this, the very little manufacturing tolerance at housing-concetrated pipe-pipe interface can cause the very big variation of magnet-coil spacing.This is not easy control at interval.In addition, have the vibration mode because of caused by extraneous vibration at work, wherein pipe and housing are opposite each other moves.This can change with the form in cycle at interval and convection current measurement volume production is given birth to adverse influence.

The present invention has four kinds of methods to address this problem.First kind, coil is not to be fixed on the housing, but is fixed on the flowtube by the sheet spring.The orientation of spring make the plane of pipe parallel coil move and holding coil-magnet is constant at interval.It is motionless that coil keeps, and this is that the far-end of spring is by being attached to the reverse displacement of equivalent on the flowtube because it is fixed between two identical springs.Because voltage offset, the simultaneous movements of flowtube or the vibration of coil are not obvious in the output signal reflection.

The second method that solves variable coil-magnet interval problem is that each sensor adopts two coils.These two coils are parallel to each other and be fixed on the flowmeter shell, and connected by lead.Flowtube is between two coils, and each pipe has two radially relative magnets of fixing on it, so that each magnet face is to coil.All four magnets (about two coils on each flowtube) have towards they same pole of coil (arctic or the South Pole) separately.In the geometry of this two coils, if housing moves about pipe, then the interval to a coil can become littler, and can become bigger equally to the interval of another coil.Because for little displacement, near linear, offset by the increase of the voltage that produces in closely-spaced side reducing by the voltage that produces in the large-spacing side about distance for magnetic field intensity.Like this, this geometry is not influenced by interval variation.

Making fixing coil not be subjected to the third method of the influence of interval variation is about pipe coil to be set like this, promptly about the main vibration mode between housing and the pipe, does not change at interval.Basic vibration mode between pipe and housing is that pipe and housing are in the internal vibration of the plane of pipe.Pipe is in phase vibration each other, pipe and housing out-of-phase vibration.This is called as the housing transverse mode.Generally be optimal pattern, so that Oscillation Amplitude is obvious with enough low frequency.The mass centre of system is near concetrated pipe.Flowtube and housing vibrate about this mass centre with rotary mode.By coil is orientated like this, promptly their plane is tangent with the sphere that center and mass centre overlap, and can guarantee to remain unchanged at interval and no matter be the housing transverse mode.By the optimal relative speed of this mode producing and this sphere is tangent and in the plane of coil.Tangent housing-pipe motion perpendicular to flowtube is the homophase pipe motion that is cancelled.Be parallel to the tangent motion of flowtube, promptly the housing transverse mode can have problems under the enough big situation of amplitude.By making coil is rectangle, causes magnet to move up and down along the straight line of coil in the vibration of this direction, and the voltage that produces is constant.

At last, coil can also be orientated by this way, and interval promptly left and right sensor becomes big each other and homophase diminishes.Phase measurement is not influenced by amplitude, because the ratio of the amplitude that is produced by two sensors remains unchanged.In a kind of " standard " sensor was provided with, sensor was positioned at the outside of flowtube corner, and corresponding to the housing transverse mode, one increases at interval and another reduces at interval.But if sensor is positioned at the outside of flowtube corner, another sensor is positioned at the inboard at crankle place, and the then interval of a left side and right sensor homophase change does not each other exert an influence to phase measurement.

For the sake of simplicity, cell winding only has been discussed up to now.More than explanation also is applicable to driver, just except generally not relating to the linearity or the phase place of drive signal.Like this, just when considering to drive benefit, driver magnet-coil spacing is only important.Because driver is usually located at the top of pipe, so coil plane is general and the center is tangent at the sphere of mass centre, and need not further take measures to keep constant at interval.

As can be seen from the above description, the invention solves and electrical connection extended to the coil of driver and be installed to the problem that sensor element brought on the pipe of vibration of coriolis flowmeter.Solve this inner connectivity problem or by with on coil actual installation to a stationary parts so that coil and actual installation corresponding magnet magnetic to the vibrating flow pipe match, or by will making the coil maintenance static on the actual flowtube that is attached to vibration of coil with the motionless spring assembly of the driven out-of-phase vibration holding coil of a relative current buret.

By reading following explanation above-mentioned and other advantages and the characteristics that the present invention may be better understood of carrying out in conjunction with the accompanying drawings

Fig. 1 is first embodiment of the present invention, expression be to be connected to cell winding and driver on a pair of flowtube through the sheet spring arrangement;

Fig. 2 is the sectional view that the cross section 2-2 along Fig. 1 is got;

What Fig. 3 represented is that part comprises magnet and the coil that is fixed to the spring assembly on a pair of flowtube;

What Fig. 4 represented is the coil that is fixed on the coriolis flowmeter frame;

That Fig. 5 puts down in writing is another possible embodiment of the present invention, and magnet and two corresponding coils of sensor are positioned on the apparent surface of a pair of flowtube;

What Fig. 6 put down in writing is a kind of flowmeter, the corresponding magnet that it has the printed-wiring board (PWB) on the stationary housing that is attached to flowmeter and is positioned at the top and the bottom of a pair of flowtube;

Fig. 7 is the sectional view that the line 7-7 along Fig. 6 is got;

What Fig. 8 represented is a flattened rectangular coil;

What Fig. 9 represented is flexible component, comprises a pair of form printed circuit coils, connecting circuit, and design is used for putting electric connector;

Figure 10 represents is the connector of flexible component of Fig. 9 of the opening of a shell that inserts coriolis flowmeter;

That Figure 11 represents is another conversion embodiment, and wherein cell winding is provided with like this, makes the concentric sphere of itself and the mass centre of center and flowmeter tangent.

What Fig. 1 represented is a kind of typical mass flowmeter 10 with Coriolis effect, it has the flowtube 12 that two cantilevers that are fixed on the concetrated pipe body 30 are installed, 14, to have essentially identical elasticity coefficient and about they moment of inertia of out-phase bending axis W-W and W '-W ' separately.

With drive coil and magnet D be installed to the top 130 and 130 of flowtube 12,14 ' between central region so that flowtube 12,14 is about axle W-W and W '-W ' out-of-phase vibration.A left side sensor L and right sensor R be installed to flowtube 12,14 tops end separately near, with the relative motion of detection flows buret 12,14.Perhaps can realize by the speed of measuring the flowtube relative motion by the motion of their output signal zero cross point on this detection or top that can be by measuring flowtube 12,14. Arm 131 and 131 on the left of flowtube 12 and 14 has ' and right side arm 134 and 134 '.Side branch downwards toward each other can coalescence be fixed to concetrated pipe parts 121 and 121 ' surface 120 and 120 ' on.Supporting baffle 140R and 140L are brazed on the arm of flowtube 12,14, and work to limit axle W-W and W '-W ', when driver D when path 156 is energized, flowtube is about axle W-W and W '-W ' out-of-phase vibration.The position of axle W-W and W '-W ' by supporting baffle 140R and 140L in flowtube side branch 131,131 ' and 134,134 ' displacement determined.

Temperature Detector 22 is installed on the side branch 131 of flowtube 14, with the approximate temperature of the temperature of measuring flowtube and the material that in flowtube, flows.This temperature information is used for determining the variation of flowtube elasticity coefficient.Driver D, sensor L, R and Temperature Detector 22 link to each other with mass flow meter 24 with 159 by path 156,157,158.Mass flow meter 24 can comprise a microprocessor, and microprocessor processes is from sensor L, and the signal that R and detecting device 22 receive is to determine the flow through mass velocity of flowmeter 10 and other measuring instrument of material, as density of material and temperature.Mass flow meter 24 also provides drive signal by path 156 to driver D, so that pipe 12 and 14 is about axle W-W and W '-W ' out-of-phase vibration.

Concetrated pipe body 30 is by housing 150,150 ' formation.Housing parts 150,150 ' can pass through ring flange 103,103 ' be attached on feeding pipe and the output pipe (not shown).Concetrated pipe body 30 is incorporated into material in the flowtube 12,14 from feeding pipe, gets back to output pipe then.When the pipe system (not shown) of the processing material of concetrated pipe ring flange 103 and 103 ' by inlet end 104 and endpiece 104 ' will measure with a transmission links to each other, material enters concetrated pipe body 30 and concetrated pipe parts 110 through the ingate (not shown) of ring flange 103, and the path (not shown) that gradually changes by housing parts 150 middle sections and flowtube 12,14 link to each other.Material by concetrated pipe parts 121 separately and assign to the left arm 131 and 131 of introducing flowtube 12,14 '.Then, material flow through upper tube parts 131,131 ' and right side arm 134 and 134 ', and be reassembled into flowtube concetrated pipe parts 121 ' independent material stream.Then, fluid be introduced into the outlet housing parts 150 ' in a passage (not shown), enter then the outlet collective component 110 '.Endpiece 104 is by having bolt hole 102 ' link to each other with the pipe system (not shown) with the ring flange 103 of aperture 101.

Fig. 2 has represented driver part D in more detail, and Fig. 2 is the sectional view that the line 2-2 along Fig. 1 is got.As Fig. 2 more clearly represented, driver part comprised 148, one entablatures 147 of 149, one left springs of a right spring and a coil 142 that is installed on the crossbeam.These parts comprise that a far-end with spring 148 and 149 is respectively installed to the sub-component on the outside surface of flowtube 14 and 12.Magnet 166 is fixed on the last outside surface of flowtube 12, and magnet 165 is fixed on the last outside surface of flowtube 14.Magnet is installed like this so that their arctic towards identical direction (promptly towards coil).The lower plane of coil 142 has enough areas to surround the magnetic field of magnet 165 and 166.When as drive operation, the AC drive signal that the unit response of Fig. 2 receives to be producing an electromagnetic field, and this electromagnetic field makes the attached flowtube on it of magnet and magnet about out-of-phase vibration each other.In this case, make flowtube that internal flow has a material at the resonance frequency place of flowtube structure about inwardly and outwards moving each other.

Left sensor L on Fig. 1 and right sensor R comprise the similar parts of parts to driver part D shown in Figure 2.So left sensor L comprises the magnet 153,154 that is separately fixed on the flowtube 14,12, make this magnet face to the coil 141 that is fixed on the crossbeam 144, crossbeam 144 is installed on the flowtube by a pair of flat elastic component 145,146 again.Similarly, right sensor R comprises the magnet 168,169 that is separately fixed on the flowtube 14,12, makes this magnet face to the coil 171 that is fixed on the crossbeam, and crossbeam is installed on the flowtube by a pair of flat elastic component 151,152 again.The relative motion of the magnet that the coil response flow buret of each sensor element is relevant with them produces the output signal of representing the flowtube motion.Output signal from the coil of sensor L and R sends mass flow measurement parts 24 to through the path 157 and 158 of Fig. 1, and parts 24 are handled these signals and produced output information about material mobile flowtube 12 and 14 in.

When as working sensor, the out-of-phase motion of the magnet response flowtube 12,14 of sensor L and R is represented the additional signal of flowtube about each other relative speed to produce.Two magnets by each sensor offset about the signal that in phase vibration produces, and do not produce the output signal that forms on conductor 157 or 158.

Fig. 3 record be a conversion embodiment, one of them drive coil 142 and pair of magnets 165 and 166 and flowtube 12 and 14 interrelate.At the embodiment of Fig. 2, magnet 165 and 166 directly is fixed on the outer surface of flowtube 12 and 14.This need be fixed to magnet on the flowtube with a kind of measure (brazing filler metal, welding etc.).The place that the embodiment of Fig. 3 is different with the embodiment of Fig. 2 is that coil and magnet are fixed on the discrete elasticity sub-component, and this sub-component comprises the elastic component 301 and 304 of crossbeam 147 and U-shaped.Coil 142 is to be fixed on the crossbeam 147 with identical mode shown in Figure 2. Magnet 165 and 166 is respectively fixed on turn right end, angle 306 and 302 of U-shaped elastic component 304 and 301.Elastic component 301 has 308, one flat part 303 and ends 302 that have 90 ° of bendings at its other end, end of 180 ° of bendings.Magnet 166 is fixed to a side of elastic part 302, and another surface of elastic part 302 is fixed on the flowtube 12 by welding or brazing filler metal.A surface of elastic part 303 also is fixed on the flowtube 12.Elastic component 304 is similar to elastic component 301.

The place that the embodiment of Fig. 3 is better than the embodiment of Fig. 2 is to allow coil and magnet to make as a discrete sub-component in advance, is fixed on flowtube 12 and 14 by any suitable attaching device then.Selection has required elasticity and flexible elastic component 301 and 304, so that crossbeam 147 and to extend to the cable 156 of coil 142 static substantially and motionless about the out-of-phase vibration of flowtube 12 and 14.For this reason, the influence that conductor 156 is not vibrated, conversely, and their rigidity, vibration damping or other mechanical properties do not have adverse influence to the out-of-phase vibration of flowtube 12 and 14.

Although the embodiment of Fig. 3 shows a kind of replacement structure of the driver D of Fig. 1 and Fig. 2, obviously, the left side of Fig. 1 can have identical structure with right sensor L with R, as shown in Figure 3.

Fig. 4 has put down in writing the design arrangement of another conversion, and wherein the non-movable coil 142 of driver D interrelates with the magnet 165,166 that is fixed on vibrating flow pipe 12 and 14. Magnet 165 and 166 directly is fixed on flowtube 12 and 14.Coil 142 be positioned near but leave the plane of magnet 165 and 166 end surfaces certain distances, between the end of coil 142 and magnet 165 and 166, to limit predetermined space.By resembling the so any suitable device of screw S coil 142 is fixed on the support with parts 402,406.The shank 404 and 405 of support is fixed on the inside surface of flowmeter shell 401.Shell 401 has surrounded the flowtube assembly 12 and 14 of Fig. 1.

The embodiment of Fig. 4 has the more uncomplicated advantage than the embodiment of Fig. 2 and 3; But the shortcoming that the embodiment of Fig. 4 attaches is that support and coil must accurately be located about shell 401, and then, shell 401 must accurately be installed on the meter assembly so that magnet 165 and 166 with coil 142 between the interval equate.In running order and when being subjected to ambient temperature effect when flowmeter, because the change of temperature influences the size at the interval between magnet and the coil 142 unequally, so, also need to expand housing or shell 401.

And, when the vibration of the relative pipe of housing causes gap periods to change, also can there be a potential problem.

The embodiment of Fig. 5 embodiment with Fig. 1 in all respects is identical, just except about the right sensor R of flowtube 14 and interrelate resemble coil R and magnet 168 such parts are positioned at the inside of flowtube, rather than resemble the sensor R of Fig. 1 and the parts that interrelate be positioned at the outside.

In Fig. 5, should note on the magnet of the magnet of left sensor element L and coil and right sensor R and the inside surface and outside surface that coil lays respectively at flowtube.This design is about the horizontal in phase vibration of flowtube or the advantage of motion, if because sensor element L and R are moved to the left they are increased at the interval between coil and the magnet separately, then their increase with amount simultaneously.Another kind of situation is that if sensor element L and R move right, then the magnet of each sensor and the interval between the coil reduce simultaneously.This design arrangement has prevented that the interval of a sensor from increasing, and the situation that the interval of another sensor reduces.If this is the case, then the relative amplitude from each signal of sensor is no longer equal, and makes the signal processing function in the mass flow measurement parts 24 more difficult.

Fig. 5 is the front elevation of the flowmeter of Fig. 1, therefore, has only represented flowtube 14 and magnet 145,155 and 158.Though in Fig. 5, do not represent flowtube 12, should know flowtube 12 with regard to adjacent below flowtube 14, and it is also understood that and be fixed with same magnets shown in Figure 1 and other parts thereon.

Fig. 6,7 and 8 have put down in writing conversion embodiment of the present invention together, wherein each a pair of printed wire (PC) plate that all contains three coils be positioned at the magnet that is equipped with cooperating a pair of flowtube last arm top and below, with driver and the sensor function of the embodiment that realizes Fig. 6.In Fig. 6, top PC wiring board is marked as parts 604.PC plate 604 be positioned at flowtube 12 and 14 above.Bottom PC wiring board parts 608 and be positioned at flowtube 12 and 14 upper level arms below.Every PC wiring board has a pancake coil of imbedding its middle part and at the flat coil of imbedding of its each end.The middle part coil of PC wiring board 604 is 602, and left end and right-hand member coil are 601 and 603.Though that sees in Fig. 6 is unclear,, bottom PC wiring board 608 has three corresponding coils of the coil with PC wiring board 604, and three coils of PC wiring board 608 are parallel and adjacent below plate 604 respective coil.

In Fig. 6, magnet 611,612 and 613 is fixed to the bottom of flowtube 14, with respectively with at the left end of bottom PC printed-wiring board (PWB) 608, middle part, the coil cooperating of right-hand member.Magnet 614,616 and 617 is fixed to the upper face of flowtube 14, with respectively with the coil 601,602 and 603 cooperatings of printed-wiring board (PWB) 604.Wiring board 604 and 608 is that 606 and 607 such supports are fixed on the housing (not shown) of flowmeter by resembling about wiring board 604.

Fig. 7 is the sectional view that the line 7-7 along Fig. 6 is got, and has represented the structure member that interrelates with sensor R in further detail.The parts of further representing in detail in Fig. 7 are included in the coil 603 of PC plate 604 and corresponding coil 603A on PC plate 608.The magnet that in Fig. 6, does not have expression and flowtube 12 to interrelate.But, in Fig. 7, represented these magnets about sensor element R, be parts 713 and 717.

The coil that should note imbedding wiring board 604 and 608 is rectangle rather than circle.These coils are illustrated among Fig. 8 in detail, suppose that wherein represented coil is the drive coil 602 of Figure 10.Front magnet 616 is fixed to the top of flowtube 14.Its pairing magnet is fixed on the flowtube 12 and is expressed as parts 714 among Fig. 8.Other coil 601 of wiring board 604 and 603 and the coil of 608 3 correspondences of wiring board also be rectangle, and identical with coil 602 shown in Figure 8.

Know with an independent magnet to replace magnet 613 and 617, and replace magnet 713 and 717 similarly, can simplify sensor R assembly.These longer monolithic magnets can be attached to the outside rather than the bottom of pipe 12 and 14.The working condition of these magnets is identical with the working condition of two parts assembly of Fig. 7.In general, the physical distance of two pipes has determined the certain coil size, especially the width of coil.Magnet can also be expanded the width of PC coil in the displacement of pipe side, reduces the sensitivity of coil to simultaneous movements and vibration thus.Relative motion between the long parallel conductor of magnet and PC coil on the direction of tubular axis can not produce any voltage or can be to the influence by the voltage that tube vibration produced.

The advantage of imbedding PC circuit board flattened rectangular coil is than lower by the thread discrete coil cost of magnetic and more can resist the influence of environment temperature.The coil of Fig. 8 is than the easier sealing of discrete coil.And, not be used in the thin lead of processing in manufacturing and the assembling process about the coil of imbedding.Compare with its discrete homologue, the coil of imbedding also has littler and other advantage of volume and weight, mainly is the manufacture process that repeats owing to very easily.

What represent on Fig. 8 is magnet 616 and 714 and the coil 606 that interrelates.These magnets are in the course of the work vertically about out-of-phase motion each other.No matter ad hoc structure shown in Figure 8 is to represent driver, or representative sensor is not always the case.It should be noted that about Fig. 8 the motion of magnet makes the magnetic field of magnet generation crossing with the conductor of basic straight line, rather than crossing with the conductor of bending.Harmonic wave when this has eliminated coil and magnet as working sensor, and by reducing when the magnet of relevant magnet crosses the conductor of bending rather than straight line, the amount of the harmonic wave that produces in the output signal of cell winding is improved the signal linearity.

Interior connection the between the coil that Fig. 6 and 7 are not shown on Fig. 6 and 7 and the electronic unit that interrelates.Fig. 9 and 10 has put down in writing preferred embodiment of the present invention, and wherein wiring board links to each other about being one another in series with 608 corresponding coils to 604.Fig. 9 and 10 has also represented the mode that these coils can link to each other with mass flow measurement parts 24.

Fig. 9 has represented that wiring board is to 604 and 608 and three coils imbedding each wiring board.The coil of wiring board 604 is 601,602 and 603.Wiring board 608 corresponding coils add a suffix A behind identical mark.Two corresponding coils of wiring board are connected in series.601 of drive coil 602 and 602A and cell winding links to each other with 603 groups of the same series connection.The coil of two wiring boards links to each other inside each other by the flexibility circuit 901 that is connected between plate 604 and the plate 608.Flexibility circuit 901 902 links to each other with the printed wire connector with connector plug 903 in the middle.These plugs are suitable for matching so that the coil line of wiring board links to each other with the incoming line of source driving signal with electronic unit 24 with matching connector.

Figure 10 represents is how the wiring board of Fig. 9 links to each other with the structure of flowmeter with connector plug.The shell 1001 of flowmeter is by part expression at length.This shell has an opening be used to pack into connector 1002 and plug 1003 thereof.Shell 1001 is fixed on pair of brackets 1004 and 1005 each the one legs, and two wiring boards are fixed on the other leg of each support.For example, about support 1004, its left leg links to each other with the shell 1001 of flowmeter, and the basal surface of its another leg links to each other with the PC plate 604 of the coil 602 that contains driver D.Figure 10 is the sectional view of Fig. 6.Printed-wiring board (PWB) 604 comprises the coil 602 of its effective plane parallel in the upper end surface of magnet 916 and 616, and magnet 916 and 616 is respectively fixed on flowtube 12 and 14.Interval between magnet 916,616 and the coil 602 keeps uniformity when work.Coil and magnet thereof for driver part and sensor element are not always the case.The flowtube 12 of Figure 10 and 14 lower surface are respectively fixed on magnet 912 and 612, match with the plane of the coil 602A of the driver D of Figure 10 in this surface.

Figure 11 record be a conversion embodiment, it makes gap size because of being fixed to the magnet on the flowtube and being fixed to vibration between the cell winding on the flowmeter stationary parts or the variation minimum of relative motion generation.Structurally similar to the embodiment of Fig. 1 place of the embodiment of Figure 11 is that it comprises flowmeter 10 casings 30, is fixed with a pair of flowtube 14 and 12, and can only sees flowtube 14 from Figure 11 on shell 30.Left side sensor L and right sensor R lay respectively at the left end and the right-hand member on the straight substantially top of flowtube 130.On Figure 11, magnet 1103 and 1104 and be fixed on the flowtube about managing 12 respective magnet (not shown).Left coil 1101 and right coil 1102 are fixed on the stationary parts (not shown) by support 1420 and 1421.At work, flowtube can be about being rigidly fixed to cell winding L and the R in phase vibration on the flowmeter with the magnet that links to each other.Need not speak more, be that this vibration that the such external condition of the vibration of its a part of system produces can make the distance (at interval) between coil and the magnet change owing to resemble flowmeter.This variation can influence the signal amplitude of coil L and R, and then damages or the reduction signal processing function.By sensor installation L and R as shown in the figure, making they and center C M is that the annulus 1120 of the centre of sphere of dynamic mass of flowtube system is tangent, the embodiment of Figure 11 make magnet and coil this relative motion influence minimum.Because coil 1101 and 1102 is rectangle as shown in Figure 8, flowtube and magnet thereof about the relative motion of coil make they about the centre of sphere CM of quality with radius 1121 and 1122 motions.This relative motion does not change size at interval, and only makes magnet about coil transversal displacement be arranged.This transversal displacement is homophase about this of each end of being positioned at flowtube top 130 to sensor magnet.The signal that is produced by each magnet has been offset in this simultaneous movements effectively, so that each coil does not produce the result of output signal as this homophase transverse movement.The structure of Figure 11 was spherical originally, so that the relative motion of above-mentioned flowtube homophase does not produce output signal in coil L and R, and no matter the flowtube travel direction is promptly left or right as shown in figure 11, or interior and outer.

The advantage of the embodiment of Figure 11 is limited to a kind of like this structure, and wherein coil 1101 and 1102 is rigidly fixed on the parts of outside.The advantage of the embodiment of Figure 11 is not suitable for the embodiment of Fig. 2 and 3, because the embodiment of Fig. 2 and 3 will stop magnet and coil that the homophase relative motion is arranged originally.

Can know that from the above description the present invention provides valuably in non-removable mode the sensor of coriolis flowmeter and the device of drive coil are installed, so that when the associated flowtube out-of-phase vibration of magnet and coil, coil does not move.This non-removable installation of coil makes coil can not change the performance of the output information that coriolis flowmeter the time produced in work or the electric conductor of precision links to each other with corresponding electronic unit by its characteristic.

Know with will be clear that, the desired explanation that the invention is not restricted to most preferred embodiment, but be included in scope of the present invention and interior other improvement and the variation of theme.

Claims (9)

1. A Coriolis flowmeter (10) having first and second flow tubes (14,12) parallel to each other; means (D) for vibrating said first and second flow tubes out of phase with each other; left and right sensors (L, R) for detecting movement of the vibrating flow tube caused by material flow through said vibrating flow tube; Said left and right sensors respectively comprise: at least two magnets (153, 154; 168, 169), each of said magnets being fixed to an adjacent portion of a different one of said flow tubes; It is characterized in that said left and right sensors also include: a coil (141; 171) mounted proximate to said magnet such that said coil remains in a stationary fixed position when said magnet vibrates with said flow tube out of phase with respect to each other; said coil has a and parallel to the common plane of the two coplanar pole faces of said two magnets; said magnets are oriented so that each of them has the same pole facing the flat surface of said coil from the same side of said coil; and The coils generate signals (157, 158) indicative of relative motion of the vibrating flow tubes in response to vibrations of the magnets secured to the vibrating flow tubes, the motions comprising Motion caused by Coriolis forces from material flow. 2. The Coriolis flowmeter of claim 1, further comprising bracket means fixed to said coil (141; 171) and a non-movable part of said flowmeter to hold said coil in said fixed position. 3. The Coriolis flowmeter of claim 1, further comprising: a pair of resilient members (145, 146; 151, 152) each having a flat body and an end respectively secured to one of said flow tubes; a beam (144) connected between the other ends of said pair of elastic members; The coil (141; 171) is connected to the middle of the beam; wherein said beam and said coil remain stationary and do not move in response to out-of-phase vibrations of said flow tubes. 4. The Coriolis flow meter of claim 3, wherein: Each of said pair of elastic members has an elongated axis, internally connecting its two ends, and the elongated axes of said pair of elastic members are parallel to each other; said beam has an elongated axis perpendicular to said pair of elastic members. Each slender axis. 5. The Coriolis flowmeter of claim 1, further comprising: The first and second parts are U-shaped and flat elastic parts; Each of said elastic members has a first end connected to a right corner end piece, one side of each of the right corner end pieces is fixed on a different one of said flow tubes (12,14), and the other side of each is secured to a different one of said magnets; a beam connected between the second ends of each of said first and second U-shaped elastic members; The coil is connected to the middle of the beam; wherein said beam and said coil remain stationary and immobile when said flow tube vibrates out of phase. 6. The Coriolis flowmeter of claim 1, wherein each of said left and right transducers is located at a different end of the upper portion of said flowmeter, said flowmeter further comprising: means (1420, 1421) for securing the coils of each sensor to a fixed part of said flowmeter such that the plane of each sensor coil is tangent to a circle whose center is at the center of said flowmeter (10) The center of the sphere of the vibrating mass coincides; said magnets are fixed on said flow tube such that the plane of each of said magnets is parallel to said plane of one of said coils; wherein said magnet cooperates with said coil such that movement of said flow tube about the center of said mass does not change the distance between said magnet and said coil while said coil remains in a fixed position. 7. The Coriolis flowmeter of claim 1, wherein each of said flow tubes has straight portions proximate and parallel to each other; and Said flowmeter also includes: a first flat printed wiring board (604) on one side of said straight portion of each flow tube; a second flat printed wiring board (608) on the opposite side of said straight portion of each flow tube; A plurality of sensor coils (601, 601A, 603, 603A), wherein each sensor coil is located at a different end of a different circuit board in a printed circuit board (604, 608) such that the plane of the flat surface of each said coil is parallel to said a plane of a circuit board surface in a circuit board; Each flow tube (12, 14) has a plurality of magnets affixed thereto, each magnet positioned between the flow tube to which it is affixed and one of said sensor coils, wherein each of said sensor coils operates to detect magnetic fields produced by different pairs of magnets secured to different flow tubes of said flow tube; and Means (607, 607A) for holding said printed wiring board stationary while said magnet and flow tube vibrate out of phase with each other. 8. The Coriolis flowmeter of claim 7, wherein said means (D) for vibrating the first and second flow tubes comprises: a plurality of driver coils (602, 602A) each positioned in the middle of a different one of said printed wiring boards (604, 608); a plurality of driver magnets (616, 612) each secured to the middle of said straight portion of a different one of said flow tubes; each of said driver magnets is located between a flow tube to which the magnet is secured and one of said driver coils, at least two magnets are located between each driver coil and said pair of flow tubes; When an excitation signal is applied to the driver coils, each of the driver coils vibrates the magnet and the stationary flow tube out of phase with each other in response to the received drive signal (156). 9. The flowmeter of claim 7, further comprising: flexible means (901) extending between said printed wiring boards for internally connecting corresponding coils of said coils on each of said printed wiring boards; connecting means (902) in the middle of said flexible means to provide an electrical interface to said coils on said printed circuit board; The connection means is adapted to be inserted into an opening in the housing of the flowmeter when assembled to internally electrically connect the coil to external wiring associated with the flowmeter.

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