EP3721180A1

EP3721180A1 - Coriolis mass flow meter

Info

Publication number: EP3721180A1
Application number: EP18804349.1A
Authority: EP
Inventors: Thomas Chatzikonstantinou
Original assignee: Heinrichs Messtechnik GmbH
Current assignee: Heinrichs Messtechnik GmbH
Priority date: 2017-12-07
Filing date: 2018-11-26
Publication date: 2020-10-14
Also published as: EP3495784A1; US11391612B2; RU2020115384A; KR20200092947A; RU2020115384A3; US20210072062A1; WO2019110353A1; CN111344539A

Abstract

The invention relates to a coriolis mass flow meter, comprising: a housing body (10), which has a flow inlet (31) and a flow outlet (32) for a fluid medium; two measurement tubes (23, 24), which are spaced apart from each other and are fastened to the housing body (10) and connect the flow inlet (31) and the flow outlet (32) to each other; at least one electrically controllable vibration exciter (42, 45) for each measurement tube (23, 24), the vibration exciter (42, 45) being designed to cause the measurement tube (23, 24) to vibrate; and at least two electrically controllable vibration sensors (41, 43, 44, 46), the vibration sensors (41, 43, 44, 46) being designed to sense the vibration of at least one of the two measurement tubes (23, 24). The vibration exciter (42, 45) and the vibration sensors (41, 43, 44, 46) are spatially fixedly fastened to the housing body (10) between the two measurement tubes (23, 24) and are designed as electromagnetic coils (1, 2, 3, 4, 5, 6). Each coil (1, 2, 3, 4, 5, 6) interacts with a permanent magnet (11, 12, 13, 14, 15, 16) fastened to one of the measurement tubes (23, 24). The permanent magnets (11, 12, 13; 14, 15, 16) are oriented in such a way that the permanent magnets (11, 12, 13; 14, 15, 16) attract each other.

Description

Coriolis mass flowmeter

The invention relates to a Coriolis mass flowmeter according to the preamble of claim 1 with a housing body having a flow inlet and a flow outlet for a fluid medium, and with two spaced apart, preferably parallel, measuring tubes, which are fixed to the housing body and connect the flow inlet and the flow outlet so that a fluid medium to be measured flows from the flow inlet through the measuring tube to the flow outlet, ie in other words, that the measuring tubes fluidly connect the flow inlet and the flow outlet. For each measuring tube at least one electrically controllable vibration exciter is provided, wherein the vibration exciter is set to set the measuring tube in vibration. Furthermore, the Coriolis mass flowmeter has at least two electrically controllable vibration transducers, wherein the vibration transducers are adapted to receive the vibration of at least one of the two measuring tubes. When measuring the flow rate of the fluid medium, the two measuring tubes oscillate against each other.

The principle of Coriolis mass flow meters is known from the prior art and is described, for example, in US Pat. No. 6,776,052 B2 or EP 1 429 119 A1. The principle of the known Coriolis mass flowmeters is described below with reference to FIG. 1, which shows in perspective a Coriolis mass flowmeter 100 'according to the prior art. In order to allow an inside view, parts of the housing and process connections are not displayed. Connecting cable and possibly Auswer- teelektronik are also not shown in Fig. 1. The connecting cables usually free between the electronic components and a device plug for connecting a device-external measurement and evaluation or to an outside of the measuring space arranged measuring and Auswer- teelektronik.

Coriolis mass flow meter 100 'according to the prior art have two measuring tubes T, 2' and a vibration exciter, which is composed of a permanent magnet coil pair 9 ', 10', to oscillate on the measuring tubes ', 2' transfer. Furthermore, two vibration sensors are provided, which are each also constructed of a permanent magnet coil pair 11 ', 13' or 12 ', 14' for receiving the vibrations of the measuring tubes T, 2 '. The permanent magnet coil pairs 9 'and 10', 1 T and 13 ', 12' and 14 'are respectively arranged on the measuring tubes T, 2', that the permanent magnets 9 ', 1 T, 12' on the Measuring tube T and the coils 10 ', 13' and 14 'are fixed to the measuring tube 2' by suitable holders. When a current pulse flows through the coil 10 'of the vibration exciter on the measuring tube 2', the permanent magnet 9 '(still polarity) fixed to the other measuring tube 1' is drawn into the coil 10 'or repelled by the coil 10'. As a result, the two measuring tubes T and 2 'are vibrated against each other.

For fixing the measuring tubes T, 2 ', at least two coupling elements 3', 4 ', sometimes also called cross struts or gusset plates, are provided for coupling the measuring tubes, in order to keep the vibration conditions for both measuring tubes 1' and 2 'comparable and to remove them from the rest isolate the device vibration. The inlet and outlet sides of the two measuring tubes 1 ', 2' are connected in pairs, each with a flow divider 5 ', 6', of which the flow divider 5 'on the inlet side, the flowing fluid to the inlets of the two measuring tubes 1', second 'and the flow divider 6' at the outlet side discharges the flowing fluid from the outlets of the two measuring tubes. The flow dividers 5 ', 6' are inlet and outlet side of a (only partially shown, inside hollow) housing 7 'recorded, so that the measuring tubes T, 2', the vibration exciter 9 ', 10', the vibration sensor 1 1 ', 13' and 12 ', 14' and the coupling elements 3 ' , 4 'are protected inside the housing 7. The housing 7 is also constructed so that the passage 8 'of cables from the interior of the device to the outside, ie to the measurement and evaluation, is possible.

In order to be able to be installed in a process line, Coriolis mass flowmeters also include process connections (not shown in FIG. 1), which on the inlet and outlet side, depending on the housing variant, either with the housing 7 'or directly with the flow dividers 5', 6 '. are connected.

In Coriolis mass flowmeters according to the prior art, vibration exciters are usually constructed in such a way that they have, for example, a permanent magnet 9 'on one of the measuring tubes 2' and a coil 10 'on the opposite measuring tube 1' in order to produce by electrical means a force effect to transmit vibrations to both measuring tubes 1 ', 2'. Each of the two vibration sensors usually also has a permanent magnet 11 ', 12' on one of the measuring tubes 1 'and one coil 13', 14 'on the opposite measuring tube 2' in order to control the vibrations of the measuring tubes 1 ', 2 to detect by induction effect. The vibration absorbers are usually mounted on the inlet and outlet side.

US Pat. No. 5,349,872 describes an arrangement of excitation and measuring coils on printed circuit boards, which are each arranged above and below the measuring tubes and fixed at angles to a housing shell.

Without flow, the signals of the two vibration sensors are in phase with each other. When the fluid flows through (fluid medium), a phase change occurs due to the different Coriolis forces on the inlet and outlet sides. Shifting the signals of the two oscillators, which is proportional to the instantaneous mass flow of the fluid medium. The mass flow of the fluid medium can thus be determined by the phase shift of the signals.

Coriolis mass flow meters 100 'according to the prior art are available for a wide variety of measuring ranges. The spectrum ranges from very large devices with a mass flow of thousands of tons per hour down to very small devices with a mass flow of one kilogram per hour and less. However, the smaller a prior art Coriolis mass flow meter 100 'becomes, the more constructive and ultimately metrological problems arise, because while most of the device's components can also be resized when resizing the meter 100' (corresponding to the measurement range), eg the measuring tubes T, 2 ', the magnets 9', 1 T, 12 ', the coupling elements 3', 4 ', etc. and even the housing 7', then a scaling towards small sizes for the coils 10 ', 13' , 14 'of the vibration exciter and vibration sensor and accordingly for their attachment elements to the measuring tubes 1', 2 ', the so-called. Coil holder, not so easy. Both bring with small Coriolis mass flow meters according to the prior art various unfavorable measurement characteristics of these devices with it and leads to design difficulties.

From US 2010/005906 A1 or US 2011/041623 A1 comparable Coriolis mass flow meters are known in which a carrier is arranged with the measuring electronics between the two measuring tubes. The measuring tubes themselves are each connected to one another via gusset plates in order to generate defined vibrations of the measuring tubes. However, this arrangement is not well scalable to smaller sizes, because smaller measurement arrangements also minor inaccuracies in the structure, eg. In the positioning of the Magnets or the gusset plates, relatively larger influence on the measurement accuracy have.

It is an object of the present invention to provide a Coriolis mass flow meter that is structurally simpler and more scalable to small sizes (for a correspondingly small measurement range).

This object is achieved by a Coriolis mass flowmeter with the features of claim 1. In the case of a Coriolis mass flowmeter of the type mentioned in the introduction, provision is made in particular for the vibration exciters and the vibration transducers to be fixed in space to the housing body, for example to a construction of the housing body, between the two measuring tubes. In the sense of the Coriolis mass flowmeter according to the invention described below, vibration exciters and vibration pickups are understood as meaning the electrically controllable components of the vibration exciters and vibration pickups, eg, coils operated electromagnetically.

With a fixed space on the housing body is meant that the vibration exciters and vibration are not on a for the implementation of the measurement relative to the housing body in vibration component, ie in particular not fixed to a measuring tube, and relative to the housing body with in Be put vibration. By this is meant that vibration exciters and vibration sensors are not fixed to a component that is vibrated according to the applied measuring principle and whose vibration is detected and evaluated for determining the mass flow of the medium. Possible due to the construction inherent vibrations of vibration exciters, vibration sensor or Ankonstruktion, compared to the metrologically required Vibrations of the measuring tubes are small (eg less than 10% or 20%) are not referred to as oscillations in the sense of this description and are regarded as space-solid. Such possible vibrations are undesirable, and it is also an aspect of the invention to avoid such unwanted vibrations. The concept proposed according to the invention also contributes to this, in that the electrically controllable parts of the vibration exciters and oscillating transducers are not arranged on parts which resonate as intended, ie in particular not on the measuring tubes.

Because the electrically controllable vibration exciters and vibration sensors are not attached to the measuring tubes and do not resonate with them during the implementation of the measuring principle, the electrically controllable vibration exciters and vibration sensors do not influence the vibration of the measuring tubes, and thus the measurement itself.

Consider, for example, the external dimensions of the coils as vibration generators and vibration transducers which, according to the design principle known from the prior art, would have to be very small if they were to be fixed on correspondingly small measuring tubes. The diameter of the coil wire would then be so thin that it could hardly be wound, and that sudden wire breaks on the connecting wires connecting the coil to the continuity lines inside the device could or would occur. Such wire breaks are the order of the day, even in the case of very large devices, because Coriolis mass flowmeters according to the state of the art, the connecting wires together with the coils, more or less uncontrolled, always resonate with them, even with measuring devices leads in correspondingly large dimensions to problems and is no longer manageable for small measuring devices in a correspondingly small measuring range. The fact that coils, coil wire and coil holders can not be reduced in size, however, brings with it further problems with small prior art Coriolis mass flowmeters. From a certain size, coils and coil holding become very heavy as compared to the measuring tubes themselves. Thus, that is, by the relatively high mass of the coils and the coil holders, the natural frequency of the measuring tubes changes gravely downwards. The devices then operate in areas of very low frequencies, eg near 100 hearts or even lower, which not only makes the devices less accurate, but also very sensitive to external influences such as vibrations, shock waves and the like. a. makes. Furthermore, due to the local increase of the mass through the coils and the coil holders, there are very high mass jumps in the system "measuring tube-fluid-coil-coil holder", so that during the operation, various self-dynamics modes occur which falsify the measurement result even further.

Also, small scale Coriolis mass flowmeters of the prior art are experiencing another problem due to downsizing. Dimensional deviations and tolerances in the production and assembly of the ever smaller components are beginning to become even more important than with large (large-scale) measuring instruments. The concatenation of dimensional deviations and tolerances is also particularly important with small measuring instruments. As a result, small devices are in most cases more difficult to manufacture and usually less accurate than larger devices. These disadvantages described above are avoided according to the invention in that the electrically controllable parts, which can not simply be scaled arbitrarily small due to the function and also require an electrical connection to the measuring and evaluation electronics, are no longer part of the oscillating system. This will see stresses (eg regarding the cable connection) and the influence on the measuring system (ie the oscillating measuring tubes) reduced.

The vibration exciters are preferably arranged between the measuring tubes in such a way that the vibration exciters for the one and the other measuring tubes act on the measuring tubes in opposite spatial directions during electrical activation. As a result, with the same and simultaneous electrical actuation of the vibration exciter, the measuring tubes are oscillated in opposite directions, so that when the fluid medium flows through the phase shift of the signals due to the coriolis effect, the flow of the fluid medium in the Mass flowmeter can be measured.

As vibration exciter and vibrating transducer according to the invention electromagnetic coils are used, for example, can be identical for all vibration exciters and vibration sensor. Each electromagnetic coil acts to generate the oscillation or to absorb the oscillation with a permanent magnet attached to one of the measuring tubes. In the electrical control of the coil acting as a vibration exciter, the latter is supplied with current, generates a magnetic field and thereby moves the permanent magnet fixed to the measuring tube. By a correspondingly set admission with current so a vibration of the measuring tube can be generated. Conversely, the movement of the permanent magnet in the coil caused by the oscillation of the measuring tube causes a current which can be measured as part of the electrical activation of the coil acting as a vibration sensor, for example by means of a current and / or voltage measurement. The use of essentially identically constructed or completely identical coils has the advantage that the vibration generation and vibration absorption are matched to one another in a simple manner. The permanent magnets on the measuring tubes can according to the size and mass of the measuring arrangement, and in particular of the measuring tubes, easily scaling and (unlike, for example, used to drive electrical components connecting cable) mechanically in the oscillation of the measuring tubes relative to them (ie, the permanent magnets) carrying measuring tubes moves.

According to the invention, the measuring tubes are arranged to run parallel. The permanent magnets on the measuring tubes are fastened opposite one another and aligned in such a way that the permanent magnets attract. When the permanent magnets are attracting, the measuring tubes, which generally oscillate in opposite directions, have the tendency to attract each other during the oscillatory movement. This is a stable state (similar to a pull bar). That is, the measuring tubes are deflected from a stable state and have a tendency to return to this state. In the case of repulsive permanent magnets, on the other hand, the measuring tubes, which oscillate in the opposite direction in the oscillatory motion tend to abut one another. This is an unstable state (similar to a push rod). That is, the measuring tubes are deflected from an unstable state and have the tendency (by instability, much like a push rod that can break in any direction), the opposite (ie, measurement relevant) vibration of the measuring tubes in any direction to randomly overlap additional deflections (in other words, to "soil") and thereby falsify the measurement results. These harmful deflections are so small that they are usually invisible to the naked eye. However, they can influence the vibration behavior and - especially with small measuring arrangements - can lead to quite significant measurement inaccuracies. These do not occur in the inventive arrangement of attractive permanent magnets. According to a preferred embodiment may be attached to the housing body a Ankonstruktion (in the sense of a holder), which carries the Schwingungser- vibrator and vibrating (so that the vibration exciter and vibrating transducer are fixed to the Ankonstruktion and are arranged between the measuring tubes). By means of sturdy components, for example correspondingly solid and non-flexible fastening elements (such as angles, supports, guides, board holders, non-flexible circuit board), the attachment can be designed such that they generate the opposing forces which are produced when the measuring tubes are vibrated intercepts and fixes the vibration exciter and vibration sensor spatially fixed to the housing body and attenuates their (unwanted) possible natural vibration or absorbs. The Ankonstruktion is designed so that the vibration exciter and vibrating transducer are arranged in the manner described in this invention between the two measuring tubes.

In a preferred development of the invention, the attachment can have at least one printed circuit board on which the electrically activatable vibration exciters and vibration pickups are fixed and can be controlled via printed conductors formed on the printed circuit board. Thus, the entire control of the sensor components and possibly also provided there measuring electronics can be done via the board. Thus, according to the invention, there are no wire connections or other electrical connections to the vibration exciters and vibration transducers, in particular the coils, or other electrical or electronic components of the measuring device (measuring electronics) which are mechanically oscillated by the oscillations with the excited oscillation of the measuring tubes be able to break and, for example, break. The measuring electronics on the board can also comprise other electrical and / or electronic components, such as eg processor, sensor (for example a temperature sensor and / or other sensors), evaluation electronics or the like, and can be integrated into an electrical circuit without having to In the measuring range between the measuring tubes, a wiring must be made, which possibly influences the measurement. This arrangement also makes it possible to attach no electronically or electrically controllable components to the measuring tubes themselves and thus to influence their natural frequency in the oscillation and thereby falsify measurement results or to provide appropriate corrections. The permanent magnets, or compensating weights provided on measuring tubes instead of the permanent magnets, may have the same design everywhere, so that no change in the vibration characteristics of one relative to the other measuring tube is produced. In addition, the permanent magnets can also scale with the measuring tubes so that the weight of the permanent magnets does not cause local changes in the oscillating angles, for example local higher-order vibrations.

In a preferred embodiment, the board via at least two fastening elements of the Ankonstruktion (7) is fixedly connected to the housing body. These fastening elements can be designed in particular as, for example, rectangular blocks. One side of the block lies flat against the housing body, and another side of the block lies flat against the board. As a result, the board is firmly fixed because each fastener has both a common bearing surface with the housing body and a common contact surface with the board. Each of the fastening elements (or each block) can also have a higher mass than the board. This counteracts unwanted vibrations of the board. Preferably, the board is fixed to the two fastening elements, for example, in which the board between the two fasteners is clamped.

In a further development of this idea of the invention, the board can be set adjustable at the two fastening elements. Preferably the board is fixed by screws which are bolted from the first block on one side of the board through through holes in the board to the second block on the other side of the board. The passage openings may have a certain play for the screws passing through them, so that the board can be finely adjusted relative to the fastening elements. Possibly. For example, the passage openings can even be formed as elongated holes, if a correspondingly large adjustment possibility is necessary or desired.

According to a preferred embodiment, exactly two vibration sensors are arranged on at least one measuring tube, wherein at least one vibration generator is provided on a measuring tube. Furthermore, according to a preferred simple embodiment, precisely one vibration exciter can be provided on each measuring tube, although embodiments may also be expedient in which exactly two or more vibration sensors and / or vibration exciters are assigned to a measuring tube.

In the case of a one-sided phase measurement (ie, an oscillation recording on only one measuring tube), the Coriolis mass flowmeter can thus have in total two oscillation exciters (one per measuring tube) and two oscillating transducers on one of the two measuring tubes, with oscillation absorbers for the other measuring tube possibly mounted, but not addressed or are responsive. If only one-sided phase measurement is provided on one measuring tube, it is also possible for balancing weights to be arranged on the other measuring tube instead of the permanent magnets, preferably with the same weight as the permanent magnets and at the same positions.

With a two-sided phase measurement (ie a vibration absorption at each measuring tube), the Coriolis mass flowmeter can thus including two vibration exciters (one for each measuring tube) and four oscillating transducers, ie two on each of the two measuring tubes.

According to a preferred embodiment, the vibration exciter can be arranged on the (each) measuring tube in the middle between the ends of the measuring tube, wherein the term "on the measuring tube" refers to the position, but not to the type of fastening according to the invention yes just done on the body and not on the measuring tube. This also applies to the vibration sensor. The ends of the measuring tube are those points on both sides of the measuring tube to which the measuring tube is fixed to the housing body. By arranging the vibration exciter in the middle between these points, it is possible with the least possible force to excite a symmetrical oscillation of the measuring tube relative to the dimensions of the measuring tube.

According to the invention, a vibration sensor may be arranged on the measuring tube between the one end of the measuring tube and the vibration exciter, and another vibration sensor may be arranged on the same measuring tube between the other end of the measuring tube and the vibration generator. Basically, the phase shift is greatest between two points that are symmetrical about the center of the measuring tube, but somewhere between the inlet and the center or outlet and center. An often preferred arrangement may be about mid-way between the vibrator and the end of the measuring tube, such as the center may include, for example, an array around the center having a range of variation about the true center of about 25%. A preferred arrangement, for example, can be between about 10% and 15% from the actual center, towards the vibration exciter. However, the arrangement is also dependent on the type and shape of the measuring tubes and can be suitably selected by the skilled person. According to a preferred embodiment of the invention, the coils of the vibration exciter can be connected in parallel and the coils of the vibration sensor can be connected in series. In this circuit arrangement, the coils of the vibration sensors form a type of generator which amplifies the voltage signal, for example approximately doubling it in typical configurations. This increases the achievable sensitivity, especially for Coriolis mass flowmeters.

A particularly suitable shape of the measuring tubes is bent because, due to the curved guidance of the fluid medium, the effect of the acting Coriolis force may possibly be relatively small in comparison to other embodiments, but results in a higher natural frequency of the measuring tubes. The more precise mechanical behavior of the measuring tubes also has metrological advantages. For example, the measuring tubes may be substantially U-shaped, wherein the outgoing legs of the "u", with which the measuring tube are fixed to the base body, may be shorter or longer than in a letter "u". A U-shape with a shortened leg compared to a letter "u" leg is a preferred embodiment here.

An embodiment which is particularly preferred according to the invention provides that the housing body of the Coriolis mass flowmeter is formed as a solid material block, preferably as a solid one-piece block of material, in each of which an opening is embedded in the flow inlet and as the flow outlet on opposite end faces each two flow channels lead from each opening to an exit in a side surface of the housing body and wherein the output of one of the flow channels in the one measuring tube and the outlet of the other of the flow channels opens into the other measuring tube. In such an embodiment, the flow channels form flow dividers to which the measuring tubes are connected. On Solid basic body according to the invention has the advantage of a high mass compared to the vibrating measuring tubes, so that undesired inherent vibrations of the measuring device or its components (not the measuring tubes) are thereby minimized.

Instead of a solid housing body according to the particularly preferred embodiment described above, according to the invention, a flow divider, which is already known from the prior art, may be provided as the flow inlet and flow outlet, to which the measuring tubes are fixed. Even so, a comparable vibration behavior of the measuring tubes can be achieved.

In addition, independently of the provision of a flow divider, the measuring tubes (also in the solid block of material proposed as preferred) can be connected to one another by coupling elements, for example in the form of transverse struts or knops. This also promotes a comparable vibration behavior of the measuring tubes.

However, an advantage of the solid material block according to the invention, preferably proposed as a housing body, lies in the fact that all of the above-mentioned additional elements (separate flow divider, coupling elements) can be dispensed with, because in the continuation of this inventive concept, the ends of the measuring tube directly may be fixed to the massively formed housing body, preferably in such a way that an outlet of a flow channel and an opening at the end of a measuring tube lie on one another. The outputs of the flow channels and the openings of the measuring tube are preferably the same size in order to achieve a uniform flow behavior of the fluid medium at the transition between the flow channel and the measuring tube. In this case, a measuring tube in each case connects the output of a flow flow channel of the flow inlet and the outlet of a flow channel of the flow outlet of the Coriolis mass flowmeter.

A structurally simple and inexpensive attachment of the measuring tubes provides that the ends of the (each) measuring tube to the housing body (or equivalent to the flow divider of the housing body, if no solid housing body is provided) are welded, wherein on the housing body (or equivalent to the flow divider of the housing body) additional material for forming the weld is provided, wherein the additional material is formed in particular by the material of the basic body. In a normal weld, welding is done with a wire applied to the weld area from outside. This can be very complicated and technically difficult with a thin weld. According to the invention, the additional material for the formation of the weld can be made available by milling into the solid housing body (material block) a round channel (in the sense of a groove), which in the middle forms an annular collar around the flow channel forms. This annular collar is then the additional material that is used instead of the welding wire to form the weld between the measuring tube and the base body formed by the solid material block. Because according to the invention can be dispensed with the additional welding wire, the welding of the measuring tube is considerably simplified with the body.

In the solid housing body, a grommet may be formed between the opening of the flow inlet and the opening of the flow outlet extending from the side surface having the outputs of the flow channels to the opposite side surface. This cable gland allows cables to be routed from the board on which the vibration generators and the vibration sensors are electrically controlled to a device connection. The device connection can, for example, also be included in the cable gland connector. It is also possible, through the cable guide, to establish a wired connection to components of the measuring electronics, for example a control processor or control computer (inside or outside the measuring device).

According to a preferred embodiment, it can also be provided that components of the measuring electronics, for example a control processor, control electronics, evaluation electronics, sensors, such as, for example, temperature sensors, are arranged on the board. The measurement electronics are also referred to in the trade as a transmitter, in the sense of measuring electronics, which controls, measures, converts and / or communicates. Integration of measuring electronics on the board results in a particularly compact design of the Coriolis mass flowmeter, in which all or part of the measuring electronics can be integrated directly into the flowmeter. The cable feedthrough and / or electrical or electronic components of the measuring electronics arranged on the board itself avoid loose cable connections in the measuring chamber of the flowmeter which could impair the measurements or could be damaged due to the vibrations excited in the measuring room.

Constructively, the two measuring tubes can be connected to one another by means of one or more transverse struts or by means of one or more gusset plates. In this way, the vibration behavior of the two measuring tubes can be standardized in particular in not too small designs of the measuring device. Since the gusset plates or cross struts are often soldered to the measuring tubes, with small scales (and thus with a low mass) measuring tubes it has been shown that different amounts of solder on the one and the other measuring tube can influence the vibration behavior differently. In order to avoid this, it can also be provided according to the invention that the Coriolis mass flowmeter has no transverse striving and / or gusset plates has. In this case, it is particularly advantageous when the housing body is designed according to the invention as a solid block of material and the ends of the measuring tubes are fixed directly to the housing body.

The Coriolis mass flowmeter can be constructed in two parts from the housing body with the components fixed thereto and a housing cover (30). Due to the few individual components, mounting the meter is easy. Because the components are firmly connected to the main body during production, no uncontrolled oscillations occur, as may arise, for example, when several components have to be joined together during commissioning.

Further features, advantages and possible applications of the invention also emerge from the exemplary embodiment of the invention described below with reference to the drawing. All described or illustrated features, alone or in any combination form the subject matter of the present invention, also independent of their summary in the claims or their back references.

Show it:

Fig. 1 in perspective a Coriolis mass flowmeter after

State of the art;

2 perspectively a Coriolis mass flowmeter according to a

Embodiment of the invention;

FIG. 3 is a top plan view of the Coriolis mass flowmeter of FIG. 2; FIG. Fig. 4 in perspective, the Coriolis mass flowmeter of FIG.

2 without vibration exciter, vibration sensor and construction;

5 perspectively the vibration exciters, vibration and

Parts of the construction of the Coriolis mass flowmeter of FIG. 2; Fig. 6 is a side view of the Coriolis mass flowmeter according to

Fig. 2;

FIG. 6a shows a cross section through the Coriolis mass flowmeter along section A-A according to FIG. 2; FIG.

FIG. 6b shows a cross section through the Coriolis mass flowmeter along section B-B according to FIG. 2; FIG.

FIG. 7 shows a longitudinal section through the middle of the Coriolis mass flowmeter according to FIG. 2; FIG.

FIG. 8 shows in perspective the Coriolis mass flowmeter according to FIG.

4 without vibration exciter, vibration sensor and construction with a detailed representation for mounting the measuring tubes; and

9 shows in perspective the Coriolis mass flowmeter according to FIG.

2 with mounted housing cover. 2 shows in perspective a Coriolis mass flow meter 100 according to a preferred embodiment of the present invention without the housing cover 30 (shown in FIG. 9) on a housing body 10 having a flow inlet 31 and a fluid medium flow outlet 32 spaced apart from each other and parallel to each other two measuring tubes 23, 24 are arranged, which are fixed to the housing body 10 and each of the flow inlet 31 and the flow outlet 32 with each other merge.

For the first measuring tube 23 is as an electrically controllable vibration exciter 42, an electromagnetic coil 2, and for the second measuring tube 24 is provided as electrically controllable vibration exciter 45, an electromagnetic coil 5. Each of the vibration exciters 42, 45 is adapted to vibrate in the associated measuring tube 23, 24, in front of which it is arranged.

Furthermore, two electrically controllable vibration sensors 41, 43 (visible in FIG. 3, hidden in FIG. 2), 44, 46 are provided in the illustrated exemplary embodiment for each measuring tube 23, 24, the vibration absorbers 41, 43, 44, 46 are adapted to absorb the vibration of at least one of the two measuring tubes 23,24. The vibration sensors 41, 43, 44, 46 are each in the form of electromagnetic coils 1, 3 (visible in FIG. 3, hidden in FIG. 2), 4, 6.

As can be seen immediately, the coils 1, 2, 3, 4, 5, 6 are not attached to the measuring tubes 23, 24 themselves, but to a Ankonstruktion 7, which is arranged between the two measuring tubes 23, 24 and fasteners 8, 9 of the Ankonstruktion 7 fixed to a part of the housing, that is spatially fixed to the housing body 10 is connected. In the illustrated embodiment, the Ankonstruktion 7 includes a board 33 with printed thereon electrical lines (not shown) associated with the coils 1, 2, 3, 4, 5, 6 (ie, in other words, the vibration exciters 42, 44 and vibration pickups 41, 43, 44, 46, these terms will become synonymous in the description of the embodiments used with coil) and, for example, with further lines (also not shown) in the interior of the measuring device 100 or external connections are connected or connectable.

In this embodiment, the coils 1, 2, 3, 4, 5, 6 are soldered to the board 33. However, the invention likewise includes other embodiments in which the coils 1, 2, 3, 4, 5, 6 are screwed, glued or fastened with other connection techniques on the board 33 or other elements of the Ankon- structures 7.

FIG. 3 shows the Coriolis mass flowmeter 100 from above, so that the vibration sensor 43 (coil 3) is also visible.

4 shows the same Coriolis mass flowmeter 100 without the attachment 7 with the board 7 and the fastening elements 8, 9, so that permanent magnets 1 1, 12, 13, 14, 15, 16 and the magnet holders 17, 18, 19, 20, 21, 22 are more visible, which are determined according to the position of the coils 1, 2, 3, 4, 5, 6 on the measuring tubes 23, 24 to cooperate magnetically with the coils 1, 2, 3, 4, 5, 6 , When the coils 2, 5 are energized (vibration) (vibration exciter 42, 45) or induced in the coils 1, 3, 4, 6 by a movement of the permanent magnets 1 1, 13, 14, 16 induced voltage or an induced Current is measured (vibration pickup 41, 43, 44, 46).

In the case of the measuring tubes 23, 24, this embodiment is two short U-tubes (U-shaped bent tubes). Coupling elements for coupling the loops are not used in this design. However, the invention concludes as well as other embodiments with, which are designed with measuring tubes 23, 24 of other shape and / or in which the measuring tubes 23, 24 coupled to each other with coupling elements (similar to the representation in FIG. 1 to the prior art) or interconnected.

For the sake of clarity, Fig. 5 shows only the board 33 of the attachment 7 with the non-movable, i.e. non-movable, means mounted thereon. spatially fixed, coils 1, 2, 3, 4, 5, 6, wherein the coil 3 is not visible and the conductor tracks on the board 33 are not shown.

FIG. 6 shows a side view of the Coriolis mass flowmeter 100, in which behind the measuring tube 24 extending from the housing body 10 the attachment 7 with the circuit board 33 held by the fastening element 9 by screwing on the housing body 10 is visible. On the board 33, the coils 4, 5, 6 are each set exactly in front of the measuring tube 24, in such a way that held in the magnet holders 20, 21, 22 on the measuring tube 24, not visible in Fig. 6 permanent magnet 14, 15th , 16 just in the windings of the coils 4, 5, 6 immerse.

This is also illustrated by the cross-section according to FIG. 6a along the line AA according to FIG. 6, which shows the coils 1, 2 or 4, 5 mounted on the board 33 in front of the measuring tubes 23 in a spatially fixed manner with the respectively associated magnet holders 17, 18 respectively 20, 21 shows. The permanent magnets 11, 12, 14, 15 are each immersed in the windings of the coils 1, 2, 4, 5 and not visible. The cross section according to FIG. 6b along the line B-B according to FIG. 6 also shows inter alia a section through the coils 2, 5 and the magnets 12, 15 of the vibration exciters 42, 45.

FIG. 7 shows a longitudinal section through the center of the Coriolis mass flowmeter 100. On the longitudinal section in FIG. 7 and at the section "AA" in FIG. 6 It can be seen that the illustrated embodiment does not require separate flow dividers (see Figures 1 - 5 ', 6') at flow inlet 31 and flow outlet 32, which are conventional in Coriolis mass flowmeters 100 'according to the prior art, because the graduation the flow of the fluid measuring medium at the flow inlet 31 to the two measuring tubes 23, 24 and the Zusammenfüh- tion this at the flow outlet 32 takes place in the illustrated embodiment directly in the opening 25 of the flow inlet 31 and in the opening 26 of the flow outlet 32, thus in the massively formed housing body 10 through flow channels 34, 35, which open from a side surface of the housing body 10 in the openings 25, 26 (see also Fig. 6a). However, the invention likewise includes other embodiments which differ in terms of flow divider from the embodiment shown here. Also, the meter 100 in the illustrated embodiment has no preferred direction of flow, ie, flow inlet 31 and flow outlet 32 may also be interchanged. However, the invention likewise includes other embodiments in which the flow inlet 31 and flow outlet 32 can be different for the purpose of optimizing the flow, and thus the flow direction is predetermined.

Furthermore, the embodiment illustrated in FIG. 7 has inlet and outlet ends via threaded connections 27, 28, to which process connections can be screwed. However, the invention also includes other embodiments as well, e.g. completely without process connections, i. with direct connection to the process line or with welded or otherwise connected (by other connection techniques) process connections.

7 also shows a possible embodiment for a cable feedthrough 29 for passing cables from the interior of the Coriolis mass flow meter 100 to the outside, eg to a measuring electronics, for power supply, for signal transmission in cases in which the measuring electronics are located inside the Device is located, for example, on the board 33 is integrated. However, the invention also includes other embodiments in which the passage of cables takes place elsewhere and in other directions.

Fig. 8 shows details of the connection of the measuring tubes 23, 24 with the solid housing body 10. In the illustrated embodiment, the measuring tubes 23, 24 welded to the housing body 10 without externally added Zusatzmateri- al. The additional material required to form a particularly durable welded joint, usually a welding wire, is provided in this embodiment by a part 36 of the housing body 10 by a special design in this area (enlargement in FIG. 8). Specifically, a collar 37 is provided as part 36, which is in the solid housing body 10 (block of material) as an edge of a round channel 38 (in the sense of a groove) is milled or is. In the middle of the annular collar 38, the flow channel 34, 35 is formed. This annular collar 38 then forms the additional material integrated into the main body 10, which is used instead of the externally applied welding wire to form the weld between the measuring tube 23, 24 and the basic body 10 formed by the solid block of material. However, the invention also includes other embodiments of connection as well, e.g. by welding with filler material, by soldering, by gluing or by other joining techniques.

9 shows in perspective a Coriolis mass flow meter 100 according to the present invention having a housing cover 30. It can be seen that the housing in the illustrated embodiment, apart from an intermediate seal (not shown), consists of only two parts bolted together consists of the housing body 10 with the components described above and the measuring range the housing body 10 covering and protective housing cover 30. However, the invention also includes other versions in which, for example, the Housing body 10 and the housing cover 30 welded together or otherwise connected to each other.

The housing body 10 is solid and has the appearance of a simple block in the embodiment shown here. However, the invention also includes other embodiments in which the external appearance is not a block, e.g. to attach the board 33 (or other attachment 7) to the housing body 10 directly (i.e., without the fasteners 8, 9) by a particular shaping of the housing body 10 or other special shapes, e.g. To attach the Coriolis mass flowmeter 100 to a stand or to a wall mount.

While a housing consisting of only two parts (apart from an intermediate seal) has various advantages, the invention also includes other embodiments which provide a housing consisting of more than two parts.

In the case of a Coriolis mass flowmeter 100 according to the present invention, in which the coils 1, 2, 3, 4, 5, 6 are no longer fixed to the housing body 10 at one of the measuring tubes 23, 24 (for example, an adapter). structure 7 or a board 33 of the Ankonstruktion 7) are set, even with a small or very small Coriolis mass flow meter 100, these coils must not be scaled down to difficult to handle dimensions. In most cases, even commercially available coils can be used. Thus, there are no exotic threading methods for coils and their attachment to the measuring tubes, and no other exotic Schwingungserreger- and Schwingungsaufnehmer principles necessary. As a result, small and very small Coriolis mass flowmeters 100 according to the present invention the invention more accurate, reliable and economical in the production than those of the prior art.

However, Coriolis mass flow meters 100 according to the present invention are also more reliable than those of the prior art for yet another reason: Because the electrically controllable coils 1, 2, 3, 4, 5, 6 (or more generally vibration exciter 42, 45 and Oscillating connecting wires from the coils 1, 2, 3, 4, 5, 6 or other electrically controllable electrical or electronic components to secondary lines, there are no oscillating connecting wires fixed in fixed space relative to the housing body 10, and if there are no oscillating connecting wires then they will not break. Connecting wires can not be made arbitrarily thick, because even with a very low stiffness connecting wires affect the natural frequency of the respective measuring tube noticeably and lead to distortions during the measurement. The lack of such connecting wires according to the invention therefore already leads to qualitatively better measuring results.

In a Coriolis mass flowmeter 100 according to the present invention, the measuring tubes 23, 24 carry only the permanent magnets 11, 12, 13, 14, 15, 16 and their associated magnet holder 17, 18, 19, 20, 21, 22. Thus, one obtains small and very small mass flow meters 100 a very light system "measuring tube fluid permanent magnet magnet holder", as for example in Fig. 4 immediately apparent. Moreover, due to the missing coils 1, 2, 3, 4, 5, 6 with the associated coil holders, this system "measuring tube fluid permanent magnet magnet holder" hardly has any local mass jumps due to the comparatively heavy coil technology in the prior art again and again, and even with larger measuring devices occur. Thus, a Coriolis mass flow meter 100 according to the invention has a simpler, calculable inherent momentum on. As a result of the missing coils 1, 2, 3, 4, 5, 6 and coil holders on the measuring tubes 23, 24, the latter also experience much smaller oscillating aerodynamic forces (fan effect). Due to the absence of these disturbing effects, ie the difficult-to-control inherent dynamics and the higher aerodynamic damping, Coriolis mass flowmeters 100 according to the present invention are more accurate overall than those according to the prior art.

Because the "meter tube fluid magnet magnet holder" system is much lighter and therefore has a much higher natural frequency than the heavier prior art systems, Coriolis mass flow meters 100 of the present invention operate at higher frequencies, e.g. according to the invention in the range of 200 Flz or at even higher frequencies than those according to the prior art. As a result, Coriolis mass flowmeters 100 according to the present invention are not only more accurate in terms of measurement but are also less sensitive to external influences such as e.g. Vibrations, shockwaves u. Ä. As such according to the prior art.

Coriolis mass flow meters 100 according to the present invention also have a completely new minimalist architecture for this type of meter. Although they have more coils 1, 2, 3, 4, 5, 6 and permanent magnets 11, 12, 13, 14, 15, 16 as such according to the prior art. Dimensional deviations and tolerance-critical components are, however, reduced to a very small number. Thus, a two-part housing (housing body 100 and housing cover 30) (with the exception of one seal) can be used with a solid base or housing body 10, which allows flow dividers and coupling elements for the measuring tubes 23, 24 to renounce. The possibility of using a printed circuit board 33 instead of internal wiring, which is found in Coriolis mass flow meters according to the prior art, further reduces movable or swingable components disposed on the body 100. The fewer components or components used, the less dimensional deviations and tolerances can occur in the production of the individual parts and assembly of the devices. For this reason as well, Coriolis mass flowmeters 100 according to the present invention, in particular for small and very small measuring devices 100, are more accurate in terms of measurement and more reliable than those according to the prior art.

Coriolis mass flowmeters 100 according to the present invention have both a one-sided phase measurement, i. on only one of the two measuring tubes 23, 24, as well as a two-sided phase measurement, i. at each of the two measuring tubes 23, 24 possible. The number of coils used 1, 2, 3, 4, 5, 6 may vary accordingly. Thus, e.g. for bilateral phase measurement, a total of six coils, i. two for the two vibration exciters 42, 45 and two-times-two for the four vibration sensors 41, 43, 44, 46, as shown in Figs. 2 and 3, necessary.

For one-sided phase measurement, however, only four coils 1, 2, 3, 5 are necessary, i. two coils 2, 5 for the two vibration exciters 42, 45 and 2 for the two vibration sensors 41, 43. In this case (the one-sided phase measurement) two coils, e.g. Coils 1, 3 or coils 4, 6 are either missing or present, but not switched or connected. In this case (the one-sided phase measurement), it also makes sense to use the permanent magnets opposite to the missing (or unswitched) coils 1, 3 or 4, 6, i. Permanent magnets 11, 13 or 14, 16 must be replaced by non-magnetic bodies of the same shape and mass.

In Coriolis mass flowmeters 100 according to the present invention, opposing coils 1, 4; 2, 5; 3, 6 electrically, depending on the desired type of vibration excitation and the phase measurement, be connected in parallel or in series. Series-connected coils can also be combined (in pairs) into one (eg longer) coil. Mutually opposite permanent magnets 11, 14; 12, 15; 13, 16 may be repulsive (ie - / - or + / +) or attractive (+/- or - / +) depending on the coil configuration and circuitry.

To the magnetic fields of opposing permanent magnets 11, 14; 12, 15; 13, 16 shield (according to the invention, for example, with strong permanent magnets) also magnetically shielding films and other magnetic shielding elements can be used.

LIST OF REFERENCE NUMBERS

1 coil

2 coil

3 coil

4 coil

5 coil

6 coil

7 Anconstruction

8 fastener

9 fastener

10 housing body

1 1 permanent magnet

12 permanent magnet

13 permanent magnet

14 permanent magnet

15 permanent magnet

16 permanent magnet

17 magnet holder

18 magnet holders

19 magnet holders

20 magnet holders

21 magnet holders

22 magnet holders

23 measuring tube

24 measuring tube

25 opening of the flow inlet 31

26 opening of the flow outlet 32nd

27 threaded connection 28 threaded connection

29 Cable entry

30 housing cover

31 flow inlet

32 flow outlet

33 board

34 flow channel to the measuring tube 23

35 flow channel to the measuring tube 24th

36 Part of the housing forming additional material 37 collar

38 round channel

41 vibration sensors

42 vibration exciter

43 vibration sensors

44 vibration sensors

45 vibration exciter

46 Vibration sensor 100 Coriolis mass flowmeter

Claims

Claims:

1 . Coriolis mass flowmeter with

- A housing body (10) having a flow inlet (31) and a flow outlet (32) for a fluid medium,

- two spaced apart measuring tubes (23, 24) which are fixed to the housing body (10) and connect the flow inlet (31) and the flow outlet (32),

- At least one electrically controllable vibration exciter (42, 45) for each measuring tube (23, 24), wherein the vibration exciter (42, 45) is arranged to set the measuring tube (23, 24) in vibration, and

- At least two electrically controllable vibration sensors (41, 43, 44, 46), wherein the vibration sensor (41, 43, 44, 46) are adapted to receive the vibration of at least one of the two measuring tubes (23, 24), wherein the Vibration exciters (42, 45) and the vibration sensors (41, 43, 44, 46) fixed in space between the two measuring tubes (23, 24) are fixed to the housing body (10) and wherein as vibration exciter (42, 45) and vibration sensor ( 41, 43, 44, 46) electromagnetic coils (1, 2, 3, 4, 5, 6) are used, each coil (1, 2, 3, 4, 5, 6) with a on one of the measuring tubes (23 , 24) fixed permanent magnet (1 1, 12, 13, 14, 15, 16) cooperates, and wherein the measuring tubes (23, 24) are arranged to run parallel and the permanent magnets (1 1, 12, 13, 14, 15 , 16) on the measuring tubes (23, 26) are mounted opposite one another, characterized in that the permanent magnets (1 1, 12, 13, 14, 15, 16) are aligned such that the permanent magnets (11, 12, 13, 14, 15, 16 ) attract.

2. Coriolis mass flowmeter according to claim 1, characterized in that on the housing body (10) an attachment (7) is provided, on which the vibration exciter (42, 45) and vibration sensor (41, 43, 44, 46) fixed are.

3. Coriolis mass flowmeter according to claim 2, characterized in that the Ankonstruktion (7) at least one circuit board (33) up, on which the electrically controllable vibration exciter (42, 45) and Schwingsaufnehmer (41, 43, 44, 46) set and formed on the board (33) conductor tracks are controlled.

4. Coriolis mass flowmeter according to claim 3, characterized in that the board (33) via at least two Befestigungselemen- te (8, 9) of the Ankonstruktion (7) is fixedly connected to the housing body, wherein each of the fastening elements (8, 9) has a higher mass than the board (33) and both a common contact surface with the housing body (10) and a common contact surface with the board (33) up, and that the board (33) on the two fastening elements ( 8, 9) is fixed.

5. Coriolis mass flowmeter according to claim 4, characterized in that the circuit board (33) is adjustably fixed to the two fastening elements (8, 9).

6. Coriolis mass flowmeter according to one of the preceding claims, characterized in that a measuring tube (23, 24) at least two vibration sensors (41, 43, 44, 46) are assigned.

7. Coriolis mass flowmeter according to claim 6, characterized in that in the Coriolis mass flowmeter (100) two vibration exciters (42, 45) and two or four vibration sensors (41, 43, 44, 46) are provided.

8. Coriolis mass flowmeter according to one of the preceding claims, characterized in that the vibration exciter (42, 45) on the measuring tube (23, 24) in the middle between the ends of the measuring tube (23, 24) is arranged that one of the vibration sensor (41, 43, 44, 46) on the measuring tube (23, 24) between the one end of the measuring tube (23, 24) and the vibration exciter (42, 45) is arranged and the other of the vibration pickups (41, 43, 44, 46) is arranged on the same measuring tube (23, 24) between the other end of the measuring tube (23, 34) and the vibration exciter (42, 45).

9. Coriolis mass flowmeter according to claim 7 or 8, characterized in that the coils of the vibration exciter (42, 45) are connected in parallel and the coils of the vibration sensor (41, 43, 44, 46) are connected in series.

10. Coriolis mass flowmeter according to one of the preceding claims, characterized in that the housing body (10) of the Coriolis mass flowmeter (100) is formed as a solid block of material in the flow inlet (31) and as a flow outlet (32) on each other opposite end faces in each case an opening (25, 26) is recessed, wherein in each case two flow channels (34, 35) from each opening (25, 26) to an output in a side surface of the housing body (10) and wherein the output of one of the flow channels (34, 35) in the one measuring tube (23, 24) and the output of the other of the flow channels (35, 34) in the other measuring tube (24 , 23) opens.

11. Coriolis mass flowmeter according to one of the preceding claims, characterized in that the ends of the measuring tube (23, 24) are fixed to the housing body (10).

12. Coriolis mass flowmeter according to claim 11, characterized in that the ends of the measuring tube (23, 24) are welded to the housing body (10), wherein on the housing body (10) additional material for the formation of the weld is provided.

13. Coriolis mass flowmeter according to one of claims 10 to 12, characterized in that in the solid housing body (10) has a cable feedthrough (29) between the opening (25) of the flow inlet (31) and the opening (26) of the flow outlet (32 ) extending from the side surface with the outputs of the flow channels (34, 35) to the opposite side surface.

14. Coriolis mass flowmeter according to one of claims 4 to 13, characterized in that components of the measuring electronics are arranged on the circuit board (33).

15. Coriolis mass flowmeter according to one of the preceding claims, characterized in that the two measuring tubes (23, 24) are interconnected by means of one or more transverse struts or by means of one or more gusset plates or that the Coriolis mass flowmeter (100) has no cross struts and / or gusset plates.

16. Coriolis mass flowmeter according to one of the preceding claims, that the Coriolis mass flowmeter (100) is constructed in two parts from the housing body (10) with the components fixed thereto and a housing cover (30).