HK1185657B - A vibrating meter including an improved meter case - Google Patents

Description

Vibrating meter including improved meter housing

Technical Field

The present invention relates to a vibrating meter, and more particularly to a vibrating meter with an improved meter case.

Background

Vibratory meters, such as, for example, densitometers, volumetric flow meters, coriolis flow meters, and the like, are used to measure one or more characteristics of a material, such as, for example, density, mass flow rate, volumetric flow rate, total mass flow, temperature, and other information. The vibrating meter includes one or more conduits, which may have various shapes such as, for example, a straight, U-shaped, or irregular configuration.

One or more of the conduits has a set of natural vibration modes including, for example, simple bending, torsional, radial, and coupled vibration modes. In order to determine the properties of the material, one or more lines are vibrated by at least one drive at a resonant frequency in one of these modes, which mode is referred to hereinafter as the drive mode. The one or more meter electronics send a sinusoidal drive signal to at least one driver, typically an electromagnet/coil combination, where the electromagnet is typically secured to the pipeline and the coil is secured to the mounting structure or another pipeline. The drive signal causes the driver to vibrate the one or more conduits at a drive frequency in a drive mode. For example, the drive signal may be a periodic current transmitted to the coil.

One or more pickoff elements detect motion of the conduit and generate a pickoff signal indicative of the motion of the vibrating conduit. The pick-up element is typically an electromagnet/coil combination, where the electromagnet is typically secured to one of the conduits and the coil is secured to the mounting structure or another of the conduits. The pickup signal is sent to one or more electronic devices; and the pick-up signal may be used by one or more electronic devices to determine a characteristic of the material or to adjust the drive signal as necessary according to well-known principles.

Typically, a vibrating meter is provided with one or more metering components such as a housing, a base, a flange, etc., in addition to the piping. Although substantially all of the additional metering components may cause measurement problems due to various vibration characteristics, the vibration characteristics of the housing are generally the most important and cause the most significant measurement problems. Thus, while the housing is the focus of the following discussion, similar vibration problems and solutions are applicable to other metering components. Measurement problems caused by various metering components are due to the difficulty in distinguishing between vibrations associated with the tubing and vibrations associated with the metering components, such as the housing. One reason for this difficulty is that the housing, like the pipeline, also has one or more natural vibration modes, including, for example, simple bending, torsional, radial, and transverse modes. The particular frequency at which a particular vibration mode is induced typically depends on factors such as the material used to construct the housing, the thickness of the housing, temperature, pressure, etc. Vibrational forces generated by the drive or other sources in the material processing system, such as the pump, can cause the housing to vibrate in a natural mode. It is difficult to generate accurate measurements of material properties where the frequency used to drive the one or more conduits in the drive mode corresponds to a frequency that causes the housing to vibrate in one of its natural modes of vibration. Vibration modes of the housing may interfere with vibration of the pipeline, resulting in erroneous measurements.

There have been various attempts in the prior art to separate the frequencies that induce the vibration modes of the housing from the frequencies that induce the vibration modes of the conduit. These frequencies may include natural resonant frequencies of various vibration modes of the housing and the pipeline into which the fluid is injected. For example, the housing may be made extremely stiff and/or massive in order to reduce the frequencies that induce the various vibration modes away from the intended drive mode of the pipeline. These options all have serious drawbacks. Increasing the mass and/or stiffness of the housing results in complex and difficult tooling, which increases cost and makes it difficult to install the vibrating meter. One particular prior art method of increasing the mass of the housing is to weld a metal weight to the existing housing. This method does not sufficiently dissipate the vibration energy in order to lower the resonance frequency of the housing. Furthermore, this approach is often costly and can produce unsightly shells.

One reason for the overlap between the drive frequency and the frequency that induces the vibrational modes within the housing is that the conduit and housing are typically constructed of similar materials, i.e., both are constructed of metal. While metal housings provide various advantages such as increased strength and explosion rating, metal housings also add significant cost to the manufacture of vibrating meters. The high cost associated with metal housings is due to the need to weld the housing. In addition, significant time and/or expense is spent in adequately separating the frequencies that induce the shell vibration modes from the drive frequency. Increasing the mass or thickness of the housing requires not only additional material, but also additional assembly time. Thus, the use of metal housings with metal tubing has various disadvantages.

The present invention overcomes the various problems and advances in the art are achieved. The present invention provides a vibrating meter with an improved meter case. The meter housing is constructed of a high damping material. The resonant frequency of the meter housing is lowered and moved away from the resonant frequency of the pipeline. Thus, the risk of the drive mode of the vibrating meter inducing a vibration mode of the meter housing is significantly reduced. Moreover, the expense associated with welded connections is also substantially eliminated by the meter housing of the present invention.

Disclosure of Invention

A vibrating meter is provided according to an embodiment of the invention. The vibrating meter includes one or more conduits constructed from a first material. The vibrating meter further includes a driver coupled to a conduit of the one or more conduits and configured to vibrate at least a portion of the conduit at one or more drive frequencies and one or more pickoffs coupled to a conduit of the one or more conduits and configured to detect motion of the vibrating portion of the conduit. According to an embodiment of the invention, the vibrating meter further comprises a housing enclosing at least a portion of the one or more conduits, the driver, and the one or more pick-offs and constructed of a second material comprising higher vibration damping characteristics than the first material.

A method of forming a vibrating meter including one or more conduits constructed of a first material is provided according to an embodiment of the invention. The method comprises the steps of coupling a driver to a conduit of the one or more conduits, the driver being configured to vibrate at least a portion of the conduit at one or more drive frequencies, and coupling one or more pickups to the conduit of the one or more conduits, the one or more pickups being configured to detect motion of the vibrating portion of the conduit. According to an embodiment of the invention, the method further comprises the step of encapsulating at least a portion of the one or more conduits, the driver and the one or more pick-offs with a housing constructed of a second material comprising higher vibration damping characteristics than the first material.

Aspect(s)

According to an aspect of the present invention, a vibrating meter includes:

one or more conduits constructed of a first material;

a driver connected to a conduit of the one or more conduits and configured to vibrate at least a portion of the conduit at one or more drive frequencies;

one or more pick-off elements connected to a conduit of the one or more conduits and configured to detect motion of the vibrating portion of the conduit; and

a housing enclosing at least a portion of the one or more conduits, the driver, and the one or more pickoffs and constructed of a second material comprising higher vibration damping characteristics than the first material.

Preferably, the housing further comprises a plurality of ribs.

Preferably, the vibrating meter further comprises a conduit opening.

Preferably, the housing further comprises a feed-through opening for one or more electrical leads.

Preferably, the vibrating meter further comprises a base connected to the housing, wherein the base is comprised of the second material.

Preferably, the first material is metal and the second material is plastic.

Preferably, the vibrating meter further comprises one or more manifolds connected to the one or more conduits and one or more manifold openings formed in the housing and adapted to receive the one or more manifolds.

Preferably, the vibrating meter further comprises a groove formed in each of the one or more manifold openings and configured to receive a sealing element connected to each of the one or more manifolds.

Preferably, the vibrating meter further comprises a breaking point formed in the housing and adapted to fail at a predetermined pressure.

Preferably, at least a portion of the vibrating meter is transparent.

According to another aspect of the invention, a method of forming a vibrating meter including one or more conduits constructed of a first material includes the steps of:

connecting a driver to a conduit of the one or more conduits, the driver being configured to vibrate at least a portion of the conduit at one or more drive frequencies;

connecting one or more pick-offs to a conduit of the one or more conduits, the one or more pick-offs being configured to detect motion of the vibrating portion of the conduit; and

at least a portion of the one or more conduits, the driver, and the one or more pick-offs are encapsulated with a housing constructed of a second material that includes higher vibration damping characteristics than the first material.

Preferably, the method further comprises the step of forming a plurality of ribs within the housing.

Preferably, the method further comprises the step of defining a conduit opening.

Preferably, the method further comprises the step of forming feed-through openings for one or more electrical leads within the housing.

Preferably, the method further comprises the step of attaching a base to the housing, wherein the base is comprised of the second material.

Preferably, the first material is metal and the second material is plastic.

Preferably, the housing includes one or more manifold openings adapted to receive one or more manifolds connected to one or more conduits, and the method further comprises the steps of attaching a sealing element to each manifold and inserting the sealing element into a groove formed in each manifold opening formed in the housing.

Preferably, the method further comprises the step of forming a fracture point within the housing adapted to fail at a predetermined pressure.

Preferably, the method further comprises the step of shaping at least a portion of the housing to be transparent.

Drawings

FIG. 1 shows a vibrating meter according to one embodiment of the invention.

FIG. 2 illustrates a portion of a housing for a vibrating meter according to one embodiment of the present invention.

FIG. 3 illustrates a vibrating meter positioned within a portion of a housing according to one embodiment of the invention.

FIG. 4 illustrates a portion of a housing for a vibrating meter according to another embodiment of the present invention.

Fig. 5 shows a housing enclosing a sensor device according to an embodiment of the invention.

FIG. 6 shows a partially exploded view of a vibrating meter according to one embodiment of the invention.

Fig. 7a shows a hysteresis diagram for a metal.

Fig. 7b shows a hysteresis diagram for plastic.

Detailed Description

Fig. 1-7b and the following description depict specific examples to teach those skilled in the art how to make and use the best mode of the invention. Some conventional matters have been simplified or omitted in order to teach the inventive principles. Those skilled in the art will appreciate variations from these examples that fall within the scope of the invention. Those skilled in the art will appreciate that the features described below can be combined in various ways to form multiple variations of the invention. Accordingly, the present invention is not limited to the specific examples described below but only by the claims and their equivalents.

Fig. 1 shows a vibrating meter 5 in the form of a meter, comprising a sensor device 10 and one or more meter electronics 20. The vibratory meter 5 may include a coriolis flow meter, an ultrasonic flow meter, a volumetric flow meter, a densitometer, or the like. Meter electronics 20 is connected to sensor device 10 by lead 100 to measure a characteristic of the material such as, for example, fluid density, mass flow rate, volumetric flow rate, total mass flow, temperature, and other information on path 26.

The sensor device 10 in this example includes a pair of flanges 101,101', manifolds 102,102', a driver 104, pickoffs 105,105', and conduits 103A, 103B. The driver 104 and the pick-offs 105,105' are connected to the conduits 103A and 103B. Driver 104 is shown secured to conduits 103A,103B at a location where driver 104 is able to vibrate vibrating portion 150 in drive mode in conduits 103A, 103B. The vibrating portions 150 in the conduits 103A,103B vibrate about the bending axes W, W', respectively. Bending axis W, W' is at least partially defined by gussets 120-123 connected to tubes 103A, 103B. It should be appreciated that there may be other portions of the conduits 103A,103B that do not vibrate or do not vibrate as desired. These so-called "non-vibrating" portions 151 of the conduits 103A,103B are typically, for example, portions below the upper strut plates 122, 123. It should be appreciated that only one vibrating portion 150 and one non-vibrating portion 151 are shown. However, because the conduits 103A,103B are substantially parallel to each other, the vibrating portion of conduit 103A is substantially the same as the vibrating portion of conduit 103B. Similarly, the non-vibrating portion of conduit 103A is substantially the same as the non-vibrating portion of conduit 103B. Likewise, the non-vibrating portion 151 is only indicated at the inlet end of the conduits 103A, 103B; the portion of the outlet below outlet gusset 123,121 is similarly the non-vibrating portion of conduits 103A, 103B.

Pick-up elements 105,105' are fixed to the conduits 103A,103B in order to detect the action of the vibrating portion 150 in the conduits 103A, 103B. Therefore, of interest in the vibrating meter is the vibration of the vibrating portion 150 in the conduits 103A, 103B. For the purposes of the following description, the components of the vibrating meter 5 other than the vibrating portion 150 of the conduits 103A,103B, the driver 104 and the pick-offs 105,105' can be classified as meter components that can also undesirably vibrate and interfere with the vibration of the conduits 103A, 103B.

Those skilled in the art will recognize that the principles described herein may be used in conjunction with any type of vibrating meter, including vibrating meters lacking coriolis flow meter measurement capability, within the scope of the present invention. Examples of such devices include, but are not limited to, vibrating densitometers, volumetric flow meters, and the like.

The flanges 101,101 'in this example are connected to manifolds 102, 102'. The manifolds 102,102' in this example are secured to opposite ends of the conduits 103A, 103B. When the sensor device 10 is inserted into a pipeline system (not shown) carrying material, the material enters the sensor device 10 through the flange 101, passes through the inlet manifold 102 to direct the entire amount of material therein into the conduits 103A,103B, flows through the conduits 103A,103B, and then back into the outlet manifold 102 'to exit the sensor device 10 through the flange 101' therein.

As described above, the conduits 103A,103B may be driven by the driver 104 in a driving mode. According to one embodiment of the invention, the drive mode may be, for example, a first out-of-phase bending mode and conduits 103A and 103B may be selected and suitably mounted to inlet manifold 102 and outlet manifold 102 'to have substantially the same mass distribution, moment of inertia, and modulus of elasticity about bending axes W, W', respectively. As shown, the conduits 103A,103B extend outwardly from the manifolds 102,102' in a substantially parallel manner. Although the conduits 103A,103B are shown as being configured to have a substantially U-shaped configuration, it is within the scope of the present invention to configure the conduits 103A,103B to have other configurations, such as, for example, a straight configuration or an irregular configuration. Also, it is within the scope of the present invention to use a mode other than the first out-of-phase bending mode as the driving mode.

In this example, when the drive modes include a first out of phase bending mode, the vibrating portions 150 of the conduits 103A,103B can be driven in opposite directions by the driver 104 about their respective bending axes W, W' at the resonant frequency of the first out of phase bending mode. The driver 104 may comprise one of a variety of known devices such as an electromagnet mounted to the conduit 103A and a counter-acting coil mounted to the conduit 103B. An alternating current may flow through the counter-acting coil to cause both conduits 103A,103B to oscillate. Appropriate drive signals may be applied to the driver 104 by one or more meter electronics 20 via leads 110. It should be appreciated that although the discussion is directed to two conduits 103A,103B, in other embodiments only a single conduit may be provided.

According to one embodiment of the invention, one or more meter electronics 20 generates and sends a drive signal to driver 104 via lead 110 to cause driver 104 to oscillate vibrating portion 150 of conduits 103A, 103B. It is also within the scope of the present invention to generate multiple drive signals for multiple drivers. The one or more meter electronics 20 can process the left and right velocity signals from the pick-up elements 105,105' to calculate a characteristic of the material, such as, for example, mass flow rate. Path 26 provides input and output means that allow one or more meter electronics 20 to interact with an operator, as is known in the art. The description of the circuitry in the meter electronics 20 or devices is not necessary for an understanding of the present invention and is omitted for simplicity of this description. It should be appreciated that the illustration in FIG. 1 is provided merely as an example of the operation of one possible vibrating meter and is not intended to limit the teachings of the present invention.

FIG. 2 shows a cross-sectional view of a portion of a housing 200 for vibrating meter 5, according to one embodiment of the present invention. The housing 200 may be provided in two or more parts and may be bonded, snapped, welded, soldered, or otherwise connected once in place. For example, fig. 2 shows only one portion 200a of the housing 200. Once assembly is initiated, a corresponding second portion of the housing 200 may be connected to the first portion 200a to substantially enclose at least a portion of the sensor device 10. In some embodiments, the two portions of the housing 200 may be connected only along a perimeter portion generally designated 210. Alternatively, two or more portions may be connected at multiple locations. A housing 200 may be provided for enclosing at least a portion of the conduits 103A,103B, the driver 104, and the pickoffs 105,105' (see fig. 3). As can be appreciated, the housing 200 may protect the conduits 103A,103B, the driver 104, and the pickoffs 105,105' as is known in the art.

Although prior art housings tend to vibrate in one or more vibration modes due to the overlap between the drive mode and the housing resonant frequency, the housing 200 of the present invention is constructed of a material having a resonant frequency that is significantly reduced and away from the drive mode frequency required to induce the vibration mode. According to one embodiment of the invention, the resonant frequency of the housing 200 is significantly away from the drive mode frequency by providing the conduits 103A,103B comprised of a first material and forming the housing 200 from a second material that exhibits higher vibration damping characteristics than the first material. As is known in the art, vibration damping is the conversion of mechanical energy (vibration) to thermal energy. The heat generated due to damping is dissipated from the mechanical system to the ambient environment. Although damping can be characterized in many different ways, one particular vibration damping characteristic is the so-called damping loss factor η. The damping loss factor η of a component can be expressed as follows:

(1)

wherein:

η is the damping loss factor;

d is the energy dissipated per unit volume per cycle; and is

W is the maximum strain energy stored during a cycle.

As can be appreciated, a higher damping loss factor should be achieved in a material that dissipates more energy per unit volume per cycle or stores less maximum strain energy over a cycle. Damping loss factors for a wide variety of materials can be obtained in look-up tables, graphs, and the like. Alternatively, the damping loss factor for a particular material may be determined experimentally. Thus, the first and second materials may be selected such that the first material comprises a smaller damping loss factor than the second material. Examples of such materials are metals and plastics/polymers. Typically, most metals have a damping loss factor in the range of about 0.001. In contrast, plastics/polymers have a damping loss factor in the range of about 0.01-2.0. Thus, by selecting a metal for the first material and a plastic/polymer for the second material, the second material is able to exhibit vibration damping characteristics that are between 10 and 2000 times higher than the vibration damping characteristics of the first material. One reason for the increased damping loss factor is because the plastic/polymer experiences viscoelastic damping and frictional losses due to contact between the fibers and the polymer. In contrast, most metals experience much lower levels of viscoelastic damping than plastics/polymers.

The different vibration damping characteristics between the first and second materials are further illustrated in fig. 7a and 7 b. Fig. 7a shows a hysteresis diagram of the input stress and the strain in response for the first material over one vibration cycle. The area contained within the ellipse is equal to the energy dissipated per cycle, which is related to the damping loss factor η described above. Fig. 7b shows a hysteresis diagram of the input stress and the strain in response for the second material over one vibration cycle. As can be seen by comparing the two figures, the area contained within the ellipse for the second material shown in fig. 7b is much larger than the area contained within the ellipse for the first material shown in fig. 7 a. Thus, both figures show that the second material has higher vibration damping properties than the first material. Thus, if the first and second materials receive substantially the same applied vibrational energy, the first material will include a higher vibrational velocity than the second material because the second material includes higher vibrational damping characteristics. Thus, the peak resonant frequency of the first material will be greater than the peak resonant frequency of the second material.

According to one embodiment of the invention, the vibrating portion 150 of the conduits 103A,103B is constructed, for example, of metal. The metal used to construct the conduits 103A,103B is titanium, which is typically and often the case in the art, due to excellent corrosion resistance and thermal properties. In certain embodiments, it may not be practical to join the first and second materials together in a fluid-tight seal. Thus, the entire conduit 103A,103B may be constructed of the first material.

According to one embodiment of the invention, when the conduits 103A,103B are constructed of metal, the housing 200 may be constructed of plastic, for example. As mentioned above, plastic exhibits much higher vibration damping characteristics, e.g., a higher damping loss factor, than metal, and thus the frequency required to induce a vibration mode within the housing 200 is significantly reduced, while the frequency required to induce a vibration mode within the conduits 103A,103B remains substantially unaffected. It should be appreciated that the specific materials used for the conduits 103A,103B and the housing 200 are merely examples and are in no way intended to limit the scope of the present invention. However, it should be appreciated that according to embodiments of the present invention, the conduits 103A,103B are made of a first material and the housing 200 is made of a second material, wherein the second material has higher vibration damping characteristics than the first material. Other examples of materials with higher vibration damping properties than metals are rubber, carbon fiber, glass fiber, graphite, glass, wood, etc. This list is not exhaustive and one skilled in the art can readily find other suitable materials that exhibit higher vibration damping characteristics that can be used for the housing 200.

When the housing 200 is constructed of plastic, the welding typically required for metal housings may be substantially eliminated, according to one embodiment of the present invention. In the illustrated embodiment, the second portion 200b of the housing 200 (see fig. 5) may be connected to the first portion 200a of the housing 200 shown in fig. 2 using an adhesive, epoxy, mechanical fasteners, snap fit, or the like. By avoiding the need to weld the housing portions together and the housing to the base, for example, the cost and complexity associated with assembling the housing 200 around the remainder of the sensor device 10 may be significantly reduced.

According to one embodiment of the present invention, the second material used to construct the housing 200 may not be as strong as the metals typically used in the prior art. Accordingly, the present invention is implemented with a number of additional features in the housing 200 in order to overcome various disadvantages typically associated with weaker materials such as plastic. In the embodiment shown in fig. 2, the housing 200 includes a plurality of ribs 201. Ribs 201 may be provided to strengthen the housing 200 while maintaining a reduced weight. The rib 201 may be added to the housing 200 by attaching the rib 201 to an existing shell 202. Alternatively, the housing 200 may be molded as is known in the art and the ribs 201 may be formed during the molding process at the same time as the shell 202 is formed. In some embodiments, ribs 201 may be provided to adjust the frequency required to induce vibration modes within housing 200. For example, by increasing the number of ribs 201 and/or the spacing between ribs 201 within the housing 200, the rigidity of the housing 200 may be increased, thereby increasing the damping of the housing 200 to further reduce the frequency required to induce vibration modes within the housing 200.

According to one embodiment of the invention, the housing 200 may further include a tube opening 206. According to one embodiment of the present invention, the manifold opening 206 is defined by a plurality of ribs 201. The conduit opening 206 may be sized and shaped to receive the conduits 103A,103B, for example. According to one embodiment of the present invention, the conduit opening 206 may comprise an area substantially equal to the area required for the conduits 103A,103B while vibrating at maximum amplitude in order to minimize pressure overlap that may occur in prior art enclosures by providing much more open space around the conduits than is required. In contrast, because the conduit opening 206 substantially surrounds the conduits 103A,103B, the housing 200 may significantly reduce the risk of the housing 200 breaking in the event of a conduit failure.

In addition to the conduit opening 206, the housing 200 may also include first and second manifold openings 203,203 'adapted to receive the first and second manifolds 102,102' of the sensor apparatus 10. The manifold openings 203,203' may further include grooves 204,204' adapted for receiving sealing elements 304,304', such as O-rings (see fig. 3).

According to an embodiment of the invention, the housing 200 further comprises a feed-through opening 205. Feedthrough openings 205 may be provided for communicating leads 100 between the driver 104, the pickoffs 105,105' and the meter electronics 20. Although the feedthrough opening 205 is shown exiting the housing 200 near the bottom, it should be appreciated that the feedthrough opening 205 may exit the housing 200 at any desired location and the particular location illustrated is in no way intended to limit the scope of the present invention.

According to one embodiment of the present invention, the housing 200 may further include a driver mounting portion 224 and a pickup mounting portion 225,225'. Driver mounting portion 224 and pickup mounting portion 225,225' may be provided in embodiments where housing 200 is used in a single tube vibrating meter. Thus, the housing 200 may be provided with a substantially fixed mounting portion that prevents vibration of the single conduit. Advantageously, no separate fixing plate or mounting part is required.

The housing 200 may provide an explosion-proof barrier. According to one embodiment of the invention, the enclosure 200 may include a blast break point 215 designed to fail at a predetermined pressure in order to safely evacuate the enclosure 200 in a particular direction. The predetermined pressure at which the blast break point 215 is designed to fail may be lower than the pressure at which the remainder of the housing 200 can be safely contained. The blast break point 215 may comprise, for example, a region of reduced thickness in the housing 200. The blast break point 215 may be formed during the molding process or may be cut after the housing 200 is formed. Although the blast break point 215 is shown near the top of the housing 200, it should be appreciated that the blast break point 215 may be located at any desired location.

Fig. 3 shows a vibrating meter 5 comprising a housing 200 according to an embodiment of the invention. As shown in fig. 3, the housing 200 may be connected to the manifolds 102,102', respectively. Because the manifolds 102,102' are also connected to the conduits 103A,103B, vibrations of the housing 200 can easily be borne by the conduits 103A,103B and disturb the measurement of the meter. The manifolds 102,102 'may be attached to the manifold openings 203,203' of the housing 200 according to known methods including, but not limited to, adhesives, brazing, welding, mechanical fasteners, and the like.

The sealing elements 304,304' are further illustrated in fig. 3. Sealing members 304,304 'may be coupled to manifolds 102,102', respectively. The sealing elements 304,304 'may be received by the grooves 204,204', for example, when the sensor device 10 is positioned within the housing 200. The sealing elements 304,304' may provide a substantially fluid tight seal between the manifolds 102,102' and the manifold openings 203,203 '. In certain embodiments, a substantially fluid-tight seal between manifolds 102,102 'and manifold openings 203,203' may provide the necessary connections for securing sensor apparatus 10 in place within housing 200. Additionally, in many embodiments, the manifolds 102,102' may be constructed of a material similar to the first material, i.e., metal, while the housing 200 is constructed of a second material, i.e., plastic. In addition to the first and second materials comprising substantially different vibration damping characteristics, the first and second materials may also comprise substantially different thermal properties. For example, the first and second materials may include different coefficients of thermal expansion. Thus, in certain embodiments, the sealing elements 304,304' may comprise rubber O-rings or similar elements to be able to accommodate differential thermal expansion when the conduits 103A,103B and the housing 200 are subjected to temperature changes. Thus, in certain embodiments, the sealing elements 304,304' may comprise a high damping material, such as rubber O-rings, and may provide additional vibration isolation and thermal compensation between the conduits 103A,103B and the housing 200 to relieve thermal stresses between the conduits 103A,103B and the housing 200.

According to one embodiment of the present invention, sealing members 304,304 'may be configured to allow manifolds 102,102' to rotate about their common axis X while substantially preventing movement in a direction perpendicular to common axis X. This restriction of lateral movement can significantly reduce the potential for damage to the flanges 101,101' and other existing equipment.

As shown in fig. 3, the driver 104 is located near the feedthrough opening 205. The lead 100 can thus easily extend from the housing 100 through the feedthrough opening 205.

Fig. 4 shows a housing 200 according to another embodiment of the invention. The embodiment shown in FIG. 4 is similar to the previously described embodiments; however, fig. 4 also shows a Printed Circuit Board (PCB) 440. The PCB440 may be connected to a portion of the housing 200 and remain substantially stationary. The PCB440 may be configured to transmit drive signals to the driver 104, to transmit pickup signals from the pickup sensors 105,105', or both. Additionally, electrical leads 400 may be connected to PCB440 and in communication with meter electronics 20, for example. Although three leads are shown, it should be appreciated that any number of leads may be provided.

According to one embodiment of the invention, PCB440 may also include a display screen 441. Display screen 441 may be configured to display various operating parameters and/or settings of vibrating meter 5. In some examples, housing 200 may include a transparent portion (see fig. 5) to allow a user to view display screen 441 without removing housing 200.

FIG. 5 shows a housing 200 substantially enclosing a portion of the vibrating meter 5, according to one embodiment of the invention. In the illustrated embodiment, the housing 200 includes a transparent portion 560. It should be appreciated that in other embodiments, substantially the entire housing 200 may be constructed of a transparent material. As described above, transparent portion 560 may be configured to view display screen 441 located within housing 200. In some embodiments, the transparent portion 560 may include a partially deformable portion to allow a user or operator to operate one or more buttons 561, for example, provided on the PCB 400. Buttons 561 may allow a user or operator to change, adjust, or view various settings of the vibrating meter 5.

As can be seen in fig. 5, a housing 200 connecting two or more portions 200a,200b together substantially encloses a portion of the sensor device 10. The only parts extending from the housing 200 are the flanges 101, 101'. It should be appreciated that the embodiment shown in fig. 5 is merely an example, and that in other embodiments, more or fewer portions of the sensor device 10 may extend from the assembled housing 200.

Also extending from the housing 200 are leads 400 that communicate with the PCB 440. The leads 400 may be in communication with the meter electronics 20, while the leads 100 previously described may provide communication between the PCB440 and the driver 104 and the pickups 105, 105'.

Fig. 6 shows a partially exploded view of a vibrating meter 5 according to another embodiment of the invention. In the embodiment shown in fig. 6, the conduits 103A,103B are connected to a base 640. The base 640 is further connected to mounting blocks 641A,641B according to one embodiment of the present invention. The mounting blocks 641A,641B can provide a means for connecting the base 640 to a process line (not shown) or a manifold (not shown).

According to the embodiment in fig. 6, the housing 200 is made of a single part instead of being provided with multiple parts. The housing 200 is further connected to a base 640. As shown in fig. 6, the housing 200 includes a plurality of positioning grooves 660. The detents 660 are provided to accommodate mechanical fasteners (not shown). Mechanical fasteners may fit within the detents 660 and engage the apertures 661 formed in the base 640 and the apertures 662 formed in the mounting blocks 641A, 641B. According to one embodiment of the invention, the mechanical fasteners may comprise, for example, U-bolts fitted to the housing 200.

According to one embodiment of the invention, the vibrating meter 5 may further include a sealing element 650 located between the housing 200 and the base 640. The sealing element 650 may comprise, for example, a rubber O-ring. According to one embodiment of the invention, a sealing element 650 may be provided for further isolating unwanted vibrations of the housing 200 from the conduits 103A, 103B. Moreover, the sealing element 650 may provide a substantially fluid tight seal between the housing 200 and the base 640.

In accordance with an embodiment of the present invention, base 640 and/or mounting blocks 641A,641B may be constructed of a second material in addition to housing 200 being constructed of a second material that is substantially different from the material used to construct conduits 103A, 103B. Alternatively, the base 640 and/or the mounting blocks 641A,641B can be constructed from a third material that is different from the first and second materials. According to one embodiment of the invention, the third material may comprise a material exhibiting higher vibration damping properties than the first material. Accordingly, the vibration frequency at which the vibration mode is induced in the base 640 or the mounting blocks 641A,641B may be significantly lower than the driving frequency. Advantageously, similar to housing 200, unwanted vibrations from base 640 and mounting blocks 641A,641B are substantially reduced.

According to one embodiment of the invention, the housing 200 is shaped such that the frequency separation between the frequency inducing the vibration modes within the housing and the drive mode frequency is greater than 1 hertz. More preferably, the frequency spacing is greater than 3-5 hertz, depending on the expected fluid density. In certain embodiments, the housing 200 may be shaped to maintain sufficient frequency separation for a range of fluid densities. For example, the resonant frequency of the casing 200 can be kept lower than that of the drive mode even when multiphase flow. The degree of frequency spacing may be adjusted depending on the particular material used for the housing 200 and/or the particular structure of the housing 200.

It will be appreciated that although the housing 200 is used as an example, the other metering components, other than the vibrating portion 150 of the conduits 103A,103B, the driver 104 and the pickoffs 105,105', may similarly be constructed of the second material in order to separate the resonant frequency of the metering components from the desired drive frequency. Thus, the present invention should not be limited to the housing 200 being constructed of a second material that exhibits greater vibration damping characteristics than the first material used to construct the vibrating portions of the conduits 103A, 103B.

The present invention provides a vibrating meter with improved measurement capabilities, as described above. Prior art vibrating meters are always faced with measurement problems caused by the overlap of vibrations between the drive mode frequency and the frequency inducing the vibration modes within the meter housing. In contrast, the present invention provides a vibrating meter with an improved meter case. An improved vibrating meter provides a conduit constructed of a first material and a housing constructed of a second material. The second material includes vibration damping characteristics different from the first material. In particular, the second material exhibits higher vibration damping characteristics than the first material. Thus, the various resonant frequencies that induce vibration modes within the meter housing constructed of the second material are significantly reduced and away from the intended drive mode frequency. Thus, the vibrating meter of the present invention does not face the vibration superimposition problem that normally affects prior art meters.

The detailed description of the embodiments presented above is not intended to be an exhaustive description of all embodiments contemplated by the inventors to fall within the scope of the invention. Indeed, those skilled in the art will recognize that certain elements of the above-described embodiments may be variously combined or deleted to create yet further embodiments, and that such further embodiments are within the scope and teachings of the present invention. It will also be apparent to those of ordinary skill in the art that the above-described embodiments may be combined in whole or in part to form additional embodiments within the scope and teachings of the invention.

Therefore, although specific embodiments of, and examples for, the invention are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize. The teachings provided herein are applicable to other vibratory systems and are not limited to the embodiments described above and shown in the drawings. Accordingly, the scope of the invention should be determined from the following claims.

Claims (19)

1. A vibrating meter (5) having one or more conduits (103A,103B), a driver (104), and one or more pick-offs (105,105'),

the one or more conduits (103A,103B) are constructed of a first material;

the driver (104) is connected to a conduit of the one or more conduits (103A,103B) and is configured to vibrate at least a portion of the conduit at one or more drive frequencies;

the one or more pick-up elements (105,105') are connected to a conduit of the one or more conduits (103A,103B) and are arranged to detect a conduit vibrating portion (150) action; and comprises:

a housing (200) enclosing at least a portion of the one or more conduits (103A,103B), the driver (104), and the one or more pick-off elements (105,105') and constructed of a second material, wherein the second material has a resonant frequency required to induce a vibration mode that is substantially reduced and away from the one or more drive mode frequencies, and wherein the second material comprises higher vibration damping characteristics than the first material.

2. The vibrating meter (5) of claim 1, wherein the housing (200) further comprises a plurality of ribs (201).

3. The vibrating meter (5) of claim 1, wherein the housing (200) further comprises a conduit opening (206).

4. The vibrating meter (5) of claim 1, wherein the case (200) further comprises a feedthrough opening (205) for the one or more electrical leads (100).

5. The vibrating meter (5) of claim 1, further comprising a base (440) coupled to the housing (200), wherein the base (440) is constructed of the second material.

6. The vibrating meter (5) of claim 1, wherein the first material is metal and the second material is plastic.

7. The vibrating meter (5) of claim 1, further comprising one or more manifolds (102,102') connected to the one or more conduits (103A,103B) and one or more manifold openings (203,203') formed in the housing (200) and adapted to receive the one or more manifolds (102,102 ').

8. The vibrating meter (5) of claim 7, further comprising a groove (204,204') formed in each of the one or more manifold openings (203,203') and configured to receive a sealing element (304,304') connected to each of the one or more manifolds (102, 102').

9. The vibrating meter (5) of claim 1, further comprising a break point (215) formed in the housing (200) and adapted to fail at a predetermined pressure.

10. The vibrating meter (5) of claim 1, wherein at least a portion (560) of the housing (200) is transparent.

11. A method of forming a vibrating meter having a driver and one or more pick-offs comprising one or more conduits constructed of a first material, comprising the steps of:

connecting the driver to a conduit of the one or more conduits, the driver being configured to vibrate at least a portion of the conduit at one or more drive frequencies;

connecting the one or more pickups to a conduit of the one or more conduits, the one or more pickups being arranged to detect motion of the vibrating portion of the conduit; and

enclosing at least a portion of the one or more conduits, the driver, and the one or more pick-off elements with an enclosure constructed of a second material, wherein the second material has a resonant frequency required to induce a vibration mode that is significantly reduced and away from the one or more drive mode frequencies, and wherein the second material comprises higher vibration damping characteristics than the first material.

12. The method of claim 11, further comprising the step of forming a plurality of ribs within the housing.

13. The method of claim 12, further comprising the step of providing a conduit opening.

14. The method of claim 11, further comprising the step of forming feed-through openings for one or more electrical leads within the housing.

15. The method of claim 11, further comprising the step of attaching a base to the housing, wherein the base is comprised of the second material.

16. The method of claim 11, wherein the first material is a metal and the second material is a plastic.

17. The method of claim 11, wherein the housing includes one or more manifold openings adapted to receive one or more manifolds connected to one or more conduits, and the method further comprises the step of attaching a sealing element to each manifold and inserting the sealing element into a groove formed in each manifold opening formed in the housing.

18. The method of claim 11, further comprising the step of forming a fracture point within the housing adapted to fail at a predetermined pressure.

19. The method of claim 11, further comprising the step of shaping at least a portion of the housing to be transparent.