Flow sensor devices and systems

A flow rate assembly can include a housing having a measurement channel extending along the housing axis and through a portion of the housing between the first and second ends of the housing, an outer cup portion positioned at least partly within the housing, and a transducer positioned within the outer cup portion and sealed from fluid flow past the outer cup portion, the transducer having a width perpendicular to the housing axis and greater than the width of the measurement channel, the transducer configured to generate an ultrasonic signal and to direct the ultrasonic signal through the measurement channel.

TECHNICAL FIELD

Certain embodiments discussed herein relate to devices and systems for measuring flow rate of fluid through pipes.

DISCUSSION OF THE RELATED ART

Many varieties of ultrasonic transducer assemblies exist, employing a variety of techniques and mechanisms for installing the transducer assemblies on a fluid conduit. However, such devices and certain components thereof have various limitations and disadvantages.

SUMMARY OF THE INVENTIONS

Traditionally, clamp-on transducers have been favored by ultrasonic flow meter manufacturers due to their one-size-fits-all transducer design that simplifies manufacturing and minimizes inventory. Clamp-on transducer type flow meters may be preferred because they have no moving parts, no wetted materials, and do not require a system shut-down for installation.

However, traditional clamp-on transducers require multiple installation details in order to operate correctly, such as: pipe material, pipe wall thickness, pipe inside diameter, pipe liner (if any), and fluid type. Furthermore, additional installation details are often difficult to obtain and detect, such as: the smoothness of the outer pipe wall, the smoothness of the inner pipe wall (defects in surface), and the eccentricity of the pipe (which may not be zero). The inner wall smoothness and eccentricity of the pipe are difficult to determine in the field and can drastically affect the accuracy of clamp-on ultrasonic flow meters.

Clamp-on transducers require a silicon grease (or similar substance) between the outer pipe wall and the bottom of the transducer to fill and eliminate any air gaps. This grease needs to be replaced periodically, especially in outdoor or dry locations, leading to increased maintenance requirements.

Due to the number of installation details needed for a successful installation of clamp-on ultrasonic transducers, successful installation may not occur in every situation. Additionally, clamp-on transducers are susceptible to being unintentionally moved by external forces, such as a passers-by knocking or hitting transducers by mistake. Any shift in the clamp-on transducer can jeopardize the flow measurement accuracy.

Installing clamp-on transducers can often frustrate an installer that is new to this type of technology. Even for those familiar with the process, properly addressing the plumbing details required for installation can be difficult, resulting in prolonged installation time periods.

While in-line transducers have also been developed, they suffer from performance challenges.

According to some variants, a flow rate assembly includes a housing having a housing axis, a first end having an inlet positioned along the housing axis, a second end having an outlet positioned along the housing axis, and/or a measurement channel extending along the housing axis and through a portion of the housing between the first and second ends of the housing, the measurement channel having a width perpendicular to the housing axis. In some embodiments, the assembly includes an outer cup portion positioned at least partly within the housing. The outer cup portion can include a head portion connected to a wall of the housing, an elongate portion connected to the head portion, the elongate portion having a first face facing the measurement channel, and/or at least one flow channel through the head portion configured to permit fluid to flow past the outer cup portion through the at least one flow channel. The assembly can include a transducer positioned within the elongate portion and sealed from fluid flow past the outer cup portion, the transducer having a width perpendicular to the housing axis and greater than the width of the measurement channel, the transducer configured to generate an ultrasonic signal and to direct the ultrasonic signal through the measurement channel. In some embodiments, a ratio of a distance between the first face of the elongate portion and the measurement channel, as measured parallel to the housing axis, to the width of the transducer is less than 4:5. In some embodiments, the first and second ends of the housing are configured to mate with open pipe end in an in-line manner.

In some embodiments, the assembly includes a second outer cup portion positioned at least partially within the housing. The second outer cup portion can include an outer head portion connected to a wall of the housing, an elongate portion connected to the head portion, and/or at least one flow channel through the head portion configured to permit fluid to flow past the outer cup portion through the at least one flow channel. In some embodiments, the assembly includes a second transducer positioned within the elongate portion of the second outer cup portion and sealed from fluid flow past the second outer cup portion, the second transducer having a width perpendicular to the housing axis and greater than the width of the measurement channel. In some embodiments, the second transducer is configured generate an ultrasonic signal and to direct the ultrasonic signal through the measurement channel toward the first transducer.

In some embodiments, the outer cup portion comprises at least one boundary wall extending between the head portion and the elongate portion and forming a boundary of the at least one flow channel, wherein the at least one boundary wall is configured to straighten flow through the at least one flow channel.

In some embodiments, the outer cup portion includes an outlet channel extending between an interior of the elongate portion and an exterior of the elongate portion.

In some embodiments, the outlet channel extends through the at least one boundary wall.

In some embodiments, the housing comprises a first housing portion, a second housing portion, and third housing portion positioned between the first and second housing portions, wherein the measurement channel extends through the third housing portion.

In some embodiments, one or more electrical components are positioned within a space between the third housing portion and the first housing portion.

According to some variants, a flow rate assembly can include a housing having a housing axis, a first end having an inlet positioned along the housing axis, a second end having an outlet positioned along the housing axis, a measurement channel extending along the housing axis and through a portion of the housing between the first and second ends of the housing, the measurement channel having a width perpendicular to the housing axis, and/or a first housing chamber between the measurement channel and the inlet, as measured along the housing axis, the first housing chamber having a tapered inner wall. The assembly can include an outer cup portion positioned at least partly within the first housing chamber. The outer cup portion can include a head portion connected to a wall of the housing, an elongate portion connected to the head portion, the elongate portion having a tapered portion between the first face and the inlet and the measurement channel, and/or at least one flow channel through the head portion configured to permit fluid to flow past the outer cup portion through the at least one flow channel. The assembly can include a transducer positioned within the elongate portion and sealed from fluid flow past the outer cup portion, the transducer having a width perpendicular to the housing axis and greater than the width of the measurement channel, the transducer configured to generate an ultrasonic signal and to direct the ultrasonic signal through the measurement channel. In some embodiments, the tapered inner wall of the first housing chamber is substantially the same shape as the tapered portion of the elongate portion of the outer cup portion.

In some embodiments, the outer cup portion is spin welded to the housing.

In some embodiments, the assembly includes a cap positioned at the first end of the housing and forming the inlet, wherein the cap is configured to engage with an open fluid conduit.

In some embodiments, the cap is spin welded to the outer cup portion.

In some embodiments, the transducer is fluidly isolated from fluid flowing through the assembly.

In some embodiments, the assembly includes an inner cup portion positioned at least partially within the elongate portion of the outer cup portion, wherein the transducer is positioned within the inner cup portion and wherein a connection between the inner cup portion and the outer cup portion forms a seal to inhibit or prevent fluid ingress into the elongate portion of the outer cup portion.

In some embodiments, the inner cup portion has a flat face facing the measurement channel.

According to some variants, a flow rate assembly includes a housing having a housing axis, a first end having an inlet positioned along the housing axis, a second end having an outlet positioned along the housing axis, and/or a measurement channel extending along the housing axis and through a portion of the housing between the first and second ends of the housing, the measurement channel having a width perpendicular to the housing axis. The assembly can include an outer cup portion positioned at least partly within the housing, the outer cup portion including a head portion connected to a wall of the housing, an elongate portion connected to the head portion, the elongate portion having a first face facing the measurement channel, and at least one flow channel through the head portion configured to permit fluid to flow past the outer cup portion through the at least one flow channel. The assembly can include a transducer positioned within the elongate portion and sealed from fluid flow past the outer cup portion, the transducer having a width perpendicular to the housing axis and greater than the width of the measurement channel, the transducer configured to generate an ultrasonic signal and to direct the ultrasonic signal through the measurement channel. In some embodiments, a ratio of a distance between the first face of the elongate portion and the measurement channel, as measured parallel to the housing axis, and the width of the measurement channel is less than 1:1.

In some embodiments, the housing comprises a first housing, a second housing, and a third housing positioned between the first and second housings, wherein the flow rate assembly includes at least one fastener that extends at least partially through each of the first, second, and third housings to connect the first, second, and third housings to each other.

In some embodiments, the flow rate assembly is configured to precisely and accurately measure flow rates through the measurement channel as low as 10 mL/min.

In some embodiments, the flow rate assembly is configured to precisely and accurately measure flow rates through the measurement channel as low as 5 mL/min.

In some embodiments, the width of the measurement channel is approximately 0.25 inches.

DETAILED DESCRIPTION OF THE INVENTIONS

While the present description sets forth specific details of various embodiments, it will be appreciated that the description is illustrative only and should not be construed in any way as limiting. Furthermore, various applications of such embodiments and modifications thereto, which may occur to those who are skilled in the art, are also encompassed by the general concepts described herein.

Ultrasonic transducer assemblies are used to measure flow characteristics of fluid flowing through pipes or other fluid lines. The transducer assemblies can include two or more transducers configured to send and receive ultrasonic signals through the fluid line and corresponding fluid. Transducer assemblies can indicate such parameters as the velocity of the fluid through the fluid line. Transducer assemblies can be used in conjunction with pumps and other devices to monitor and/or control flow rates through fluid lines.

The transducers used in traditional transducer assemblies often must be precisely aligned with the longitudinal axis of the fluid line on which they are installed. Misalignment of the transducers can increase the likelihood that the ultrasonic signals sent from the first transducer will not be received by the second transducer. Further, many transducer assemblies rely on reflection of the ultrasonic signals off of the interior surface of the pipe. Thus, the assemblies must be carefully calibrated to account for the pipe characteristics (e.g., size, material, etc.) as well as the fluid characteristics (e.g., composition, temperature, etc.).

Inline type ultrasonic flow meters can reduce installation time and improve flow measurement accuracy since several difficult to determine variables necessary for a successful installation may be removed. Inline flow meters having axially-aligned transducers can reduce or eliminate the need to reflect signals off of the interior walls of the pipe. As such, the transducers may not need to be realigned when used with different fluid types.

Furthermore, some embodiments of an inline flow meter can reduce inventory holding cost. Since the annular diameter of the flow passage of the inline flow meter can be controlled at the time of manufacture, several models with varying annular diameters can be made. External pipes of varying diameters may be connected to each model of the inline flow meter. Therefore, in some embodiments, an inline flow meter having a given diameter may be used with a range of pipe diameters. This reduces the amount of inventory required while also improving the measuring accuracy, due to the other variables, identified above, that may be controlled during manufacture of the flow meter.

An embodiment of a flow meter assembly10is illustrated inFIG. 1. The flow meter assembly10has a first end14and a second end18. The ends14,18of the sensor assembly10can be configured to connect in-line with a pipe (not shown). In some embodiments, each of the first and second ends14,18are similar or identical in structure.

The flow meter assembly10can include a central portion20. The central portion20can extend between the first and second ends14,18. In some embodiments, the first and second ends14,18comprise respective caps22aand22b. The central portion20can comprise a housing26. The housing26can include a housing axis27. The housing axis27can extend along a length of the housing26and through the first and second ends14,18of the flow meter assembly10. In some embodiments, the housing axis27is parallel to the length of the housing26. One or more sensors, transducer, and/or other components can be positioned within the housing26and/or within the caps22a,22b. The caps22a,22bcan be constructed separate from the housing26and can be connected to opposite ends of the housing26during assembly. In some embodiments, the caps22a,22bare removable from the housing26after assembly.

As illustrated inFIG. 2, each of the caps22a,22bcan include first mating portion28a,28b. The first mating portions28a,28bcan be configured to couple with a pipe in an in-line manner. For example, the first mating portions28a,28bcan each be configured to be inserted into an end of a pipe. Fasteners, welding, adhesives, and/or other connection methods/structures can be used to connect the caps22a,22b(e.g., the first mating portions28a,28b) to the pipe ends. The caps22a,22bcan include apertures32a,32b(FIG. 4) configured to facilitate fluid flow from the pipes through the housing26.

As illustrated inFIGS. 2-3, the caps22a,22bcan include second portions30a,30b. The second portions30a,30bhave a diameter D1greater than the diameter D2of the first mating portions28a,28b. The second portions30a,30bcan be configured to inhibit or prevent over-insertion of the caps22a,22binto the pipes and/or into the housing26. For example, the second portions30a,30bcan be sized to abut the ends of the pipes and the ends of the housing26. The first mating portions28a,28bcan extend from the second portions30a,30b.

Referring toFIG. 4, the caps22a,22bcan include third portions34a,34b. The third portions34a,34bcan be connected to the second portions30a,30band extend in a direction opposite the first mating portions28a,28b. The third portions34a,34bcan have outer diameters that are sized to fit at least partially within the housing26. For example, the third portions34a,34bcan be inserted into the housing26when the caps22a,22bare mated with the housing26. The inner diameter D3of the third portions34a,34bcan greater than the inner diameter D4of the apertures32a,32b. As illustrated, the inner diameter D3of the third portions34a,34bforms cap chambers36a,36b. The cap chamber36ais in fluid communication with the aperture32ain the cap22aand the cap chamber36bis in fluid communication with the aperture32bin the opposite cap22b.

The housing26can include one or more housing chambers38a,38b. For example, the inner diameter D5of the housing26near the first and second ends14,18of the assembly can define the housing chambers38a,38b. The housing chambers38a,38b. The inner diameter D5can be greater than the inner diameter D4of the apertures32a,32b. In some embodiments, the inner diameter D5defining the housing chambers38a,38bcan be within ±15%, within ±12%, within ±9%, and/or within ±5% of the inner diameter D3of the third portions34a,34bof the caps22a,22b.

The housing26can include a measurement channel40. The measurement channel40can extend along the housing axis27(FIG. 5). In some embodiments, the measurement channel40is straight and parallel to the housing axis27. The measurement channel40can have a diameter D6. As illustrated, the measurement channel40can have a constant diameter along its length. The diameter D6of the measurement channel40can be less than one or both of the diameters D4, D5of the cap chambers. In some embodiments, the diameter D6of the measurement channel40is less than ½, less than ⅓, less than ¼, and/or less than ⅕ of the diameter D5of the housing chambers38a,38b. In some applications, the diameter D6of the measurement channel is less than or equal to 1 inch, less than or equal to 0.75 inches, less than or equal to 0.5 inches, and/or less than or equal to 0.25 inches. For example, the diameter D6of the measurement channel40can be approximately 0.25 inches.

As illustrated inFIGS. 4-5, the flow meter assembly10can include one or more sensor assemblies44a,44b. The sensor assemblies44a,44bcan be positioned within one or both of the cap chambers36a,36band housing chambers38a,38b. In some embodiments, the sensor assemblies44a,44bare positioned outside of and on opposite sides of the measurement channel40.

The sensor assemblies44a,44bcan each include an outer cup portion46a,46b. The sensor assemblies44a,44bcan each include a transducer assembly54a,54b. The transducer assembly54a,54bcan be positioned at least partially within the outer cup portion46a,46b. The sensor assembly44a,44bcan include a cap56a,56bconfigured to seal one side of the sensor assembly44a,44band inhibit or prevent ingress of fluid into the sensor assemblies44a,44bfrom the interior of the flow meter assembly10. The flow meter assembly can include one or more seals45(e.g., O-rings) positioned between the sensor assemblies,44a,44band the caps22a,22b, and/or housing26.

In some embodiments, as discussed in more detail below, the sensor assemblies44a,44binclude an outlet port60a,60bconfigured to facilitate access of wires (not shown) or other components into the sensor assemblies44a,44bfrom outside of the flow meter assembly10. As illustrated, the outlet ports60a,60bcan be aligned with housing ports62a,62bwhich extend through the walls of the housing26. Wires passed through the ports60a,60b,62a,62bcan be connected to controllers, power sources, and/or other electrical components. Isolation of the wires from the fluid flowing through the meter assembly10can allow for flow measurements without concern for corrosion of the wires or other components within the sensor assemblies44a,44b. Such isolation can allow for flow rate measurement in corrosive chemicals and other fluids. One or more controllers (not shown) may be used to adjust components within the flow meter10in response to changes in fluid types, temperatures, and other factors.

As illustrated inFIGS. 7-8, the outer cup portion46a,46bcan include a head portion48a,48b. The outer cup portion46a,46bcan include an elongate portion52a,52b. The elongate portion52a,52bcan be connected to the head portion48a,48band extend therefrom in a direction parallel to the channel axis27. One or more flow channels68a,68bcan be formed through the head portion48a,48b. The flow channels68a,68bcan facilitate fluid flow past the sensor assemblies44a,44bthrough the flow meter assembly10. The flow channels68a,68bcan be bounded by boundary walls66a,66b. The boundary walls66a,66bcan be curved form rounded ends to the flow channels68a,68b, as measured in a plane perpendicular to the channel axis.

The sensor assembly44a,44bcan include a key feature70a,70b(e.g., a protrusion, indentation, or other keying feature). The key feature70a,70bcan be configured to fit into or onto an alignment feature72a,72b(e.g., a protrusion, indentation, or other keying feature) of the housing26. Interaction between the key feature70a,70band alignment feature72a,72bcan help to ensure proper alignment between the outlet ports60a,60band the housing ports62a,62b. The head portion48a,48bcan include one or more seal channels77configured to receive and/or align the seal(s)45.

Referring toFIGS. 9-10, the transducer assembly54a,54bcan include an inner cup portion76a,76b. The inner cup portion76a,76bcan be configured to house and/or receive a transducer82a,82b. In some embodiments, a transducer backing83a,83bcan be positioned within the inner cup portion76a,76bbehind the transducer82a,82b. In some embodiments, the backing83a,83bis an elastomer, epoxy, or other material configured to inhibit transmission of ultrasonic signals from the transducers82a,82bthrough the backing83a,83b.

As illustrated inFIG. 4, the transducer82a,82bcan have a width or diameter D7. The diameter D7of the transducer can be greater than the diameter D6of the measurement channel40. For example, the diameter D6of the transducer82a,82bcan be at least 5% greater, at least 8% greater, at least 12% greater, at least 25% greater, at least 35% greater, at least 50% greater, and/or at least 100% greater than the diameter D6of the measurement channel40. In some embodiments, the diameter D7of the transducer82a,82bis at least 0.1 inches, at least 0.2 inches, at least 0.25 inches, at least 0.3 inches, at least 0.4 inches, at least 0.75 inches, and/or at least 1 inch. For example, the diameter D7of the transducer82a,82bcan be approximately 0.375 inches.

Referring back toFIGS. 9-10, the inner cup portion76a,76bcan include a head portion78a,78b. The inner cup portion76a,76bcan include an elongate portion80a,80bconnected to and extending from the head portion78a,78b. The transducer82a,82bcan be positioned within the elongate portion80a,80bat or near the end of the elongate portion80a,80bopposite the head portion78a,78b.

The head portion78a,78bof the inner cup portion76a,76bcan be configured to engage with a portion of the elongate portion52a,52b. In some embodiments, the head portion78a,78bof the inner cup portion76a,76bis welded, adhered, or otherwise connected to the elongate portion52a,52bor some other portion of the sensor assembly44a,44b.

The elongate portion52a,52bcan include a channel84a,84b. The channel84a,84bcan extend through the entirety of the elongate portion52a,52b. In some embodiments, one end of the channel84a,84bis closed (e.g., the end facing the opposite sensor assembly44a,44b). The channel84a,84bcan be sized and shaped to receive the elongate portion80a,80bof the inner cup portion76a,76b.

As illustrated inFIG. 11, the elongate portion52a,52bcan have a tapered end86a,86b(e.g., the end closest to the opposite sensor assembly44a,44b). In some embodiments, the elongate portion52a,52bhas an overall “bullet” shape. When assembled, the transducer82a,82bcan be positioned at or near the end of the elongate portion52a,52b(e.g., the tapered end) opposite the head48a,48b. In some embodiments, this end of the elongate portion52a,52bhas the smallest diameter of any portion of the elongate portion52a,52b.

The transducer82a,82bcan have an overall flat shape. For example, the transducer82a,82bcan have a disc shape with a front side88a,88band a back side90a,90b. The front side88a,88bof the transducer82a,82bcan be the side facing the transducer72a,72bon the other end of the housing26. The respective front sides88a,88bcan be parallel to each other and can be positioned along the housing axis27. Such alignment can facilitate successful transmission of ultrasonic signals between the two transducers82a,82b. In some embodiments, a wire conduit92a,92bis connected to the back side90a,90bof the transducer82a,82b. The wire conduit92a,92bcan help guide electrical wires away from the transducer82a,82band toward the outlet port60a,60bwhen the sensor assembly44a,44bis assembled.

The transducer82a,872bcan be positioned along the housing axis27. The width (e.g., diameter) of the transducer82a,82bcan be greater than the diameter D6of the measurement channel40. The transducer82a,82bcan be positioned behind a portion of the inner cup portion76a,76bthrough which the transducer82a,82b. For example, the inner cup portion76a,76bcan include a wave guide portion94a,94b. The wave guide portion94a,94bcan be on the end of the inner cup portion76a,76bclosest the measurement channel40. The wave guide portion94a,94bcan have a wave guide face96a,96bfacing toward the wave guide face96a,96bof the opposite sensor assembly44a,44b. The wave guide faces96a,96bcan be flat and positioned along the housing axis to facilitate direction of the transducer signals parallel to the housing axis27. The wave guide faces96a,96bcan be parallel to each other. In some embodiments, the wave guide faces96a,96bhave a concave configuration to focus the transducer signals inward toward the housing axis27. In some embodiments, the wave guide96a,96bhas a convex shape to direct the ultrasonic waves outward toward the walls of the measurement channel40.

As illustrated inFIG. 5, the wave guide faces96a,96bcan be positioned close to the ends of the measurement channel40as measured parallel to the housing axis27. In some embodiments, distance D8between the wave guide faces96a,96band the ends of the measurement channel40are less than 2 inches, less than 1.5 inches, less than 1 inch, less than 0.75 inches, less than 0.55 inches, less than 0.3 inches, and/or less than 0.1 inches, as measured parallel to the housing axis27. In some embodiments, the distance D8between the wave guide faces96a,96band the measurement channel40is approximately 0.22 inches, as measured parallel to the housing axis27. Maintaining a close distance between the wave guide faces96a,96band the ends of the measurement channel40can increase the quality of the measurements obtainable by the transducers82a,82b. For example, maintaining a close distance can reduce the turbulence in the flow by maintaining a smooth flow path between the flow channels68a,68band the measurement channel40. This flow path can transition with relatively little or no diffusion from the flow channels68a,68band the measurement channel40. Reducing turbulence in the flow between the wave guide faces96a,96band the measurement channel40can reduce the noise in the signal measured by the transducers82a,82b. In some embodiments, flow rates as low as 15 mL/min, as low as 10 mL/min, and/or as low as 5 mL/min can be measured.

The ratio between the distance D8and the diameter D7of the transducer82a,82bcan be less than 2:1, less than 3:2, less than 4:3, less than 7:8, less than 3:4, less than 1:2, and/or less than 1:4. In some embodiments, the ratio between the distance D8and the diameter D7of the transducer82a,82bis approximately 3:5. The ratio between the distance D8and the diameter D6of the measurement channel40can be less than 2:1, less than 5:4, less than 6:5, less than 8:9, less than 1:2, less than 1:3, and/or less than 1:4. In some embodiments, the ratio between the distance D8and the diameter D6of the measurement channel40is approximately 9:10. Maintaining close ratios between the distance D8and the diameters D6and D7can help to maintain a smooth flow at the entrance and exit of the measurement channel40. Maintaining smooth flow (e.g., low turbulence) can reduce the noise in the signal measured by the transducers82a,82band can allow for measurement of small flow rates.

Referring toFIG. 12, the housing chamber38a,38bon either end of the housing26can have a tapered portion98a,98b. The tapered portion98a,98bcan extend to the measurement channel40.

Referring back toFIG. 5, the flow meter assembly10can be symmetric about a plane (not shown) perpendicular to the housing axis27and positioned halfway along the length of the housing26. Each of the cap apertures32a,32b, transducers82a,82b, and measurement channel40can be positioned along the housing axis27to facilitate a substantially straight fluid flow path through the flow meter assembly10.

Either of the cap apertures32a,32bcan function as an inlet to the flow meter assembly10, while the opposite cap aperture32a,32bserves as the outlet to the flow meter assembly10. For the purposes of discussion, the cap aperture32aon first end14will be referred to as the inlet, while the cap aperture32bon the second end18will be referred to as the outlet. Using inlets and outlets that are coaxial or otherwise aligned with the fluid flow path through the assembly10can reduce introduction of turbulence that would otherwise occur if lateral or oblique inlets/outlets were used.

Fluid (e.g., a liquid) that flows through the inlet32apasses into the cap chamber36a. The cap chamber36acan have filleted and/or chamfered internal surfaces to provide a smooth fluid flow surface. Providing a smooth flow surface can inhibit bubble generation within the fluid. The fluid in the cap chamber36ais directed through the flow channels68aof the sensor assembly44ainto the housing chamber38a. The boundary walls66acan reduce turbulence and/or straighten the fluid flow through the system. For example, the boundary walls66acan inhibit vortical fluid flow through the channels68a. The flow stabilization provided by the boundary walls66a,66bcan permit positioning of the flow meter assembly10closer to a bend in a piping system than may have been possible without the boundary walls66a,66b. The fluid then passes between the tapered end86aof the elongate portion52aand the tapered portion98aof the housing chamber38a. The fluid is accelerated into the measurement channel40.

The flow rate of the fluid is measured by the transducers82a,82bas the fluid flows through the measurement channel40. Each of the transducers82a,82bcan send and receive ultrasonic signals when measuring flow rate through the measurement channel40. The fluid then passes between the tapered end86bof the elongate portion52band the tapered portion98bof the housing chamber38b. After passing through the housing chamber38b, the fluid is directed through the channels68bof the sensor assembly44band into the cap chamber36b. The fluid then passes out through the outlet32band into the pipe with which the cap22bis mated.

Utilizing a narrow measurement channel40(e.g., a channel narrower than the transducers82a,82b) can facilitate accurate and reliable measurement of very low liquid flow rates. For example, a flow meter assembly10as described in the present disclosure can measure flow rates as low as 15 mL/min, as low as 10 mL/min, and/or as low as 5 mL/min. Accurately measuring low flow rates such as those recited above can be especially beneficial in applications where chemicals or other components need to be added to another fluid at a reliably low level (e.g., due to safety considerations). This is often needed in small municipalities, individual homes, and other small scale water treatment and/or water deliver environments.

Another advantage provided by the flow meter assembly10is the ability to measure fluid velocity without needing to reflect ultrasonic signals off of the walls of the housing26or of any other component in the system. For example, flow meters which measure reflected signals must precisely align and position the transducers to ensure that the signals from each transducer will be received by the other transducer. Such alignment challenges in reflected-signal systems can be further exacerbated when the temperature and/or composition of the fluid changes, as these changes can require repositioning/realignment of one or both of the transducers. Further, imperfections, corrosion, sediment, and/or other abnormalities on the surface of the pipe walls can adversely affect the accuracy of reflected signals. Signal strength can also suffer when the ultrasonic signals are reflected due to phenomena such as dispersion of the signal and absorption of a portion of the signal by the reflecting surface. The above-recited challenges associated with reflected-signal systems can be avoided by the flow meter10, as the ultrasonic signals generated by the transducers82a,82bare sent directly to the opposite transducer without reflection.

In some embodiments, one or more of the components within the caps22a,22band/or housing26may be removed for cleaning, repair, or other maintenance. For example, one of the caps22a,22bmay be disconnected from the housing26, allowing a user access to the sensor assembly44a,44b.

FIGS. 13-21illustrate an embodiment of a flow meter assembly110. The flow meter assembly110includes some structures and functions that are the same as or similar to the structures and functions described above with respect to the flow meter assembly10. Components of the flow meter110that are similar or the same in structure and/or function as the components of the flow meter10are labeled with a like reference number, wherein a value of “100” is added. For example, the wave guide faces196a,196bof the flow meter110are similar in structure and function as the wave guide faces96a,96bof the flow meter10. Unless otherwise noted below, the like components of the flow meter110are the same as or similar in structure and/or function as the like elements of the flow meter10.

As illustrated inFIGS. 13-15, the flow meter assembly110can include a plurality of housing components. For example, the flow meter assembly110can include a first housing portion126a, and a second housing portion126b. The first and second housing portions126a,126bcan be similar in structure to each other and can be mirrored about the longitudinal axis of the assembly110. In some embodiments, one or both of the first and second housing portions126a,126bcan include apertures135though which fasteners131or other components can be inserted. The fasteners131(FIG. 16) can be configured to hold the first and second housing portions126a,126btogether when assembled.

The flow meter assembly110can include a third or inner housing portion126c. The third housing portion126ccan be positioned at least partially between the first and second housing portions126a,126b. In some embodiments, a housing interior123(FIG. 17) is formed between the third housing portion126cand the first and second housing portions126a,126b. The fasteners131can be configured to pass through at least a portion of the third housing126cto secure the third housing126cto and/or between the

As illustrated inFIG. 16, the assembly110can include one or more seals127a,127b. The seals127a,127bcan be positioned between two or more of the housing portions126a,126b,126c(collectively “126”) to seal the housing interior123. In some embodiments, the seals127a,127bare shaped and sized to match one or more surfaces of the housing portions126. The seals127a,127bcan be configured to seal the interface between the third housing portion126cand the first housing portion126a, and the interface between the third housing portion126cand the second housing portion126b, respectively.

One or more electrical components (e.g., circuit boards, controllers, wireless or wired transmitters, batteries, sensors, memory units, processors, etc.) can be positioned at least partially within the housing interior123. As illustrated, electrical components143,145can be positioned on one or both sides of the third housing portions126c. Grommets129or other sealing structures can be used to facilitate passage of wires and/or cables from an exterior of the housing portions126to the housing interior123. In some embodiments, the assembly110is completely wireless and without holes or other access structures into the housing interior123when the assembly110is assembled.

In some embodiments, two or more components of the assembly110are connected to each other via spin welding. For example, the caps122a,122bcan be spin welded to the outer cup portions146a,146bof the sensor assemblies144a,144b. In some embodiments, the outer cup portions146a,146bare spin welded to the third housing126c. Spin welding the components to each other can realize a number of benefits. For example, the spin welding process can create a chemical bond between the welded components that can reduce or eliminate the need for using separate O-rings or other sealing structures. This can increase the life of the assembly110and reduce the need to replace the seals over time. In some configurations, as illustrated inFIG. 17, the voids167are formed in various portions of the assembly110to capture material (e.g., flakes, chips, or other material) generated during the spin welding process.

Preferably, the various marked distances and diameters inFIG. 17are the same as or similar to the distances and diameters described above with respect toFIGS. 4 and 5. For example, widths/diameters D13, D14, D15, D16, and D17can be the same as or similar to the widths/diameters D3, D4, D5, D6, and D7, respectively. The distance D18can be the same as or similar to the distance D8. As illustrated inFIG. 17, the wave guide faces196a,196bcan extend beyond the inner cup portions176a,176, respectively, in a direction toward the measurement channel40. This extension can create a step between the wave guide faces196a,196band the inner cup portions176a,176to inhibit or prevent formation of bubbles on wave guide faces196a,196b. The respective ratios between the distances and widths/diameters in the assembly110can be the same as or similar to those distances and widths/diameters described above with respect to assembly10.

As illustrated inFIGS. 17 and 18, the inner walls of the housing chambers138a,138bcan have the same or similar slopes/tapers as the elongate portions152a,152bof the outer cup portions146a,146b. Utilizing similar shapes, curves, and/or tapers between the inner walls of the housing chambers and the outer walls of the elongate portions can reduce turbulence in the flow of fluid through the system, as instances of nuzzling and diffusing can be reduced.

As illustrated inFIGS. 16-21, the outer cup portions146a,146band third housing126ccan include one or more ports or channels through which wires or cables can be inserted into an interior of the elongate portions152a,152bof the outer cup portions146a,146b. As illustrated inFIG. 21, outlet channels160a,160bcan extend through the boundary walls166a,166bof the outer cup portion146a,146b. The outlet channels160a,160bcan have inner ports163a,163band outer ports165a,165b. The outlet channels160a,160bcan be aligned with housing ports162a,162bto facilitate passage of wires (e.g., the wires169a,169bofFIG. 17) into the interiors of the elongate portions152a,152b.

The terms “approximately”, “about”, “generally” and “substantially” as used herein represent an amount close to the stated amount that still performs a desired function or achieves a desired result. For example, the terms “approximately”, “about”, “generally,” and “substantially” may refer to an amount that is within less than 10% of the stated amount.

While the preferred embodiments of the present inventions have been described above, it should be understood that they have been presented by way of example only, and not of limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the inventions. Thus the present inventions should not be limited by the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents. Furthermore, while certain advantages of the inventions have been described herein, it is to be understood that not necessarily all such advantages may be achieved in accordance with any particular embodiment of the inventions. Thus, for example, those skilled in the art will recognize that the inventions may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein.