Piezoelectric cable flow sensor

A flow sensor for a pipe includes a housing defining an interior chamber; a mounting adapter that is circumferentially coupled to an open proximal end of the housing; and a piezoelectric cable that at least partially extends within the interior chamber of the housing. The piezoelectric cable includes a piezoelectric material.

BACKGROUND

Field

This application relates generally to flow sensors. More particularly, embodiments of the subject matter relate to flow sensors for placement across a flow path in a fluid distribution system.

Background Technology

Flow sensors can detect the rate of flow of fluid in a closed system such as water in a pipe system. Many flow sensors are unusable or undesirable in certain systems, such as potable water distribution systems, because of the material compositions and other characteristics of the sensor. Pipe systems are also subject to leaks and pipe bursts that can be difficult to detect and locate and can cause significant damage to the system and surrounding property, as well as significant interruptions in service to downstream users, if not located and fixed quickly.

It is desirable to have flow sensor or sensors that are configurable for placement across a flow path in a fluid distribution system to timely indicate if a pipe leak or failure has occurred to minimize collateral damage. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.

SUMMARY

Described herein is a flow sensor and a method of fluid flow in a pipe system. In one aspect, the flow sensor is configurable for insertion into a pipe and can comprise a housing defining an interior chamber; a mounting adapter circumferentially coupled to an open proximal end of the housing; and a piezoelectric cable. In a further aspect, the piezoelectric cable can comprise at least one of an inner conductive layer, a piezoelectric material layer that can at least partially circumferentially surround and contact the inner conductive layer, and an outer conductive layer that can at least partially circumferentially surround and contact the piezoelectric material layer. It is contemplated that a distal portion of the piezoelectric cable can extend within the interior chamber of the housing.

In another aspect, the method for detecting fluid flow in a pipe forming a portion of a pipe system can comprise inserting at least a portion of the flow sensor into the interior cavity of the pipe; positioning a portion of a housing of the flow sensor across a flow path of a fluid within the interior cavity of the pipe; vibrating the flow sensor with fluid flow impacting at least a portion of a housing of the flow sensor within the pipe system; and measuring an output from the flow sensor, the output comprising, for example and without limitation, a charge or a voltage.

DETAILED DESCRIPTION

As used throughout, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a resistor” can include two or more such resistors unless the context indicates otherwise.

In one aspect, disclosed is a flow sensor and associated methods, systems, devices, and various apparatus. The flow sensor comprises a housing and a piezoelectric cable. It would be understood by one of skill in the art that the disclosed flow sensor is described in but a few exemplary embodiments among many. No particular terminology or description should be considered limiting on the disclosure or the scope of any claims issuing therefrom.

An exemplary flow sensor100is illustrated inFIG. 1. In one aspect, the flow sensor100can comprise an elongated external member110, a piezoelectric cable200(shown inFIG. 2), a cylindrical tube210(shown inFIG. 2), a mounting adapter120, a stiffening sleeve130, and an RCA connector140. In a further aspect, the external member110can define an elongated interior void that is configured or otherwise sized and shaped to operatively receive and house the cylindrical tube210and a distal portion201(shown inFIG. 2) of the piezoelectric cable200. It is contemplated that the external member110can be circumferentially coupled to an open proximal end121of the mounting adapter120by, for example and without limitation, welding, press-fitting, epoxy or other adhesive, a threaded connection being formed integrally with a portion of the mounting adapter, or any other like mechanism for connection.

In one aspect, the external member110can define an outer surface111that defines a rectangular cross-section relative to a longitudinal axis of the external member. In one aspect, the rectangular cross-section can be a square cross-section. Optionally, it is contemplated that the outer surface111can define other uniform geometric cross-sections in various other aspects, including but not limited to circular, triangular, pentagonal, hexagonal, octagonal cross-sections and the like, and can comprise any number and combination of flat and curved sides. In another aspect, at least a portion of the outer surface111can optionally be textured or roughened, such as by hand with sandpaper or machining, to increase a drag coefficient of fluid flow across the outer surface111. In this aspect, the external member can also comprise an endcap112at a distal end113, which is configured to close the distal end113of the external member110. Optionally, the distal end113can be closed by epoxy or any other filling, having a preformed end formed integrally with the external member110, crimping the distal end113, or any other like mechanism suitable for closing the distal end113.

In another aspect, the mounting adapter120can comprise a hex bushing122, a reducing hex nipple123, and a coupling nut124. In this aspect, the reducing hex nipple123can be configurable to couple the hex bushing122to the coupling nut124. The hex bushing122defines the open proximal end121, and the hex bushing122, the reducing hex nipple123, and the coupling nut124in combination define a substantially co-axial passage configured or otherwise sized and shaped to receive the piezoelectric cable200that is configured to pass through the mounting adapter120. Optionally, it is contemplated that the mounting adapter120can be any mechanisms or combination of mechanisms, with hex or non-hex features, that allow the flow sensor100to mount on a pipe wall saddle310(shown inFIG. 3) or otherwise mounted on a pipe300(shown inFIG. 3).

In one aspect, the stiffening sleeve130can extend from the mounting adapter120to the RCA connector140. In this aspect, a first end131of the stiffening sleeve130can be circumferentially coupled to the coupling nut124and a second end132of the stiffening sleeve130can be circumferentially coupled to the RCA connector140by a band133. In this aspect, it is contemplated that the first end131can be circumferentially coupled to the coupling nut124and the second end132can be circumferentially coupled to the RCA connector140by any other mechanisms in other aspects, including, but not limited to, heat-shrinking, adhesives, hose clamps, interference fits, or other bands.

FIG. 2shows an exploded view of the flow sensor100with the stiffening sleeve130and the RCA connector140removed. In one aspect, the external member110can further comprise a tapered distal end220that is configured to hold the tube210within the external member110. However, optionally, it is contemplated that the distal end220need not be tapered in other aspects.

In one aspect, the tube210can exemplarily comprise acetal homopolymer, such as sold under the trade name Delrin®, though the tube210can comprise other materials in other aspects, such as various metals, polymers and the like. In this aspect, the piezoelectric cable200is complementarily sized and shaped to extend through the mounting adapter120and to be received within the tube210, which is also complementarily sized and shaped to be received within the external member110. In one aspect, the tube210can be fully enclosed within the external member110, with the tube210comprising a length substantially equal to a length of the external member110, though, optionally, it is contemplated that the tube210can be longer or shorter than the external member110in other aspects.

In one aspect, the piezoelectric cable200is a coaxial cable and can comprise a distal end202, a proximal end203, a jacket204, an outer conductive layer205, and an inner conductive layer206. The distal end202can be closed and covered by the jacket204or open. In one aspect, the proximal end203of the piezoelectric cable200can be configured to be coupled with the RCA connector140. In this aspect, to exemplarily couple the proximal end203of the piezoelectric cable200with the RCA connector140, a portion of the outer conductive layer205can be peeled away from the inner conductive layer206and separated from the inner conductive layer206with a portion of the jacket204. Thus, in this exemplary aspect, the inner conductive layer206and the outer conductive layer205can thereby be coupled to the RCA connector140by soldering the layers205,206to respective connection portions of the RCA connector140. Other connectors140can be used in other aspects, such as F connectors, banana plugs, or any other like mechanism for connecting the piezoelectric cable200to a measuring device.

In another aspect, the coupling nut124can comprise internal threading for attachment to complementary external threading on a reduced end224of the reducing hex nipple123, as shown inFIG. 4. Likewise, the hex bushing122can comprise internal threading for attachment to complementary external threading on an enlarged end223of the reducing hex nipple123, as shown inFIG. 4.

Referring now toFIGS. 3 and 4, the flow sensor100is shown mounted on the pipe wall saddle310. In one aspect, the pipe wall saddle310can be mounted on an exterior surface301of the pipe300. In this aspect, it is contemplated that the external threading of the hex bushing122can be attached to complementary internal threading of a saddle hex bushing311. Similarly, the saddle hex bushing311is attached to internal threading of a neck312of the pipe wall saddle310. In this aspect, the neck312and the saddle hex bushing311can define bores therethrough that are aligned with a sensor hole402formed in the pipe300. In one aspect, the sensor hole extends from the exterior surface301to an interior surface401of the pipe300. In this aspect, attachment of the hex bushing122to the saddle hex bushing311extends a portion of the external member110through the saddle hex bushing311, the neck312, and the sensor hole402.

FIG. 4shows a cross-sectional view of the pipe300, pipe wall saddle310, and flow sensor100and illustrates a portion of each of the external member110, the tube210, and the piezoelectric cable200extending through the sensor hole402into an interior400of the pipe300into an operating position across a flow path of a fluid traveling through the pipe system in the interior400of the pipe300. In one aspect, the portion of the external member110inserted into the interior400of the pipe300can be at least three inches long, though other aspects can have a length of three inches or less. In one aspect, the pipe wall saddle310can comprise a first saddle segment305and a second saddle segment306that are configured to be coupled together with nut-and-bolt fasteners307a,b.

FIG. 4also illustrates the piezoelectric cable200extending through the external member110, tube210, mounting adapter120, and stiffening sleeve130. In this aspect, the distal end202of the piezoelectric cable200is exemplarily positioned proximate to the distal end113of the external member110such that the piezoelectric cable200can extend into the interior400of the pipe300approximately the same distance as the external member110. In a further aspect, the piezoelectric cable200can be embedded within an interior chamber of the tube210such that at least a portion of the piezoelectric cable200is positioned in contact with an inner surface of the tube210and is held fixedly in place relative to the tube210. In this aspect, it is contemplated that the piezoelectric cable200will not move relative to the tube210. Likewise, the tube210can be embedded within an interior chamber of the external member110such that at least a portion of the tube210contacts an inner surface of the external member110and is held fixedly in place relative to the external member110. In this aspect, it is contemplated that the tube210consequently will not move relative to the external member110. In other aspects, the tube210may not be present and the piezoelectric cable200can be embedded within the interior chamber of the external member110such that at least a portion of the piezoelectric cable200contacts an inner surface of the external member110and is held fixedly in place relative to the external member110.

FIG. 5shows one aspect of the piezoelectric cable200. The piezoelectric cable200inFIG. 5is a coaxial cable and comprises the inner conductive layer206, a piezoelectric material layer500, the outer conductive layer205, and the jacket204. The piezoelectric material layer500circumferentially surrounds and contacts the inner conductive layer206, which is a center core comprising 20 AWG stranded silver-plated copper wire. The outer conductive layer205is a copper braid and circumferentially surrounds and contacts the piezoelectric material layer500. The jacket204is extruded high-density polyethylene and circumferentially surrounds and contacts the outer conductive layer205, though other nonconductive materials can be used to form the jacket204. The piezoelectric material layer500can partially circumferentially surround or be adjacent to the inner conductive layer206in other aspects, and the outer conductive layer205can partially circumferentially surround or be adjacent to the piezoelectric material layer500in other aspects. The outer conductive layer205and inner conductive layer206can comprise other conductive materials or combination of materials at various to allow electrical conduction through the piezoelectric cable200in other aspects.

The piezoelectric material layer500inFIG. 5comprises polyvinylidene difluoride (“PVDF”) piezo film tape. Two adjacent pieces of the tape are spiral-wrapped around the inner conductive layer206, and the outer conductive layer205surrounds the tape. The inner conductive layer206, the piezoelectric material layer500, and the outer conductive layer205are thereby all in electrical communication with each other.

FIG. 6shows another aspect of the piezoelectric cable200. The piezoelectric cable200ofFIG. 6is similar to the piezoelectric cable200ofFIG. 5except that the piezoelectric material layer500is a piezo PVDF copolymer that is extruded directly onto and around the inner conductive layer206and then surrounded by the outer conductive layer205. The copolymer can be polarized. In various other aspects, the piezoelectric material layer500can comprise any other piezoelectric material that can generate a charge or a voltage, including but not limited to copoylmers and terpolymers of PVDF and piezoelectric crystals.

FIG. 7Ashows a graph illustrating the response of the flow sensor100ofFIG. 1at various pump RPM during testing of the flow sensor100in a fluid system. As shown inFIG. 7A, the first harmonic, or peak, at each RPM is around 35 Hz.FIG. 7Bshows a graph illustrating the overall spectrum levels as a function of the pump speed. As shown inFIG. 7B, the spectrum levels appear to scale with the pump RPM.FIG. 7Cillustrates the effect of band-limiting the root mean square (“RMS”) levels and shows that the RMS levels scale with the pump RPM. As shown inFIG. 7C, the optimum low pass-filter setting for all of the pump RPM is in the range of 30 Hz to 40 Hz, which coincides with the beam natural frequency. The flow sensor100ofFIG. 1thereby is able to determine the rate of flow within the fluid system.

In one aspect, the flow sensor100can be installed in a pipe system by tapping a sensor hole402from the exterior surface301of the pipe300to the interior surface401of the pipe300. It is contemplated that the sensor hole402can be formed by known tapping methods such as the use of a ball valve, or a similar valve, and a drill mounted on the pipe wall saddle310to drill the sensor hole402through the ball valve, or can be pre-formed prior to mounting the pipe wall saddle310. In various aspects, use of a ball valve mounted on the pipe wall saddle310allows the flow sensor100to be mounted on the pipe wall saddle310after the ball valve is closed and the drill is removed. The flow sensor100can thereafter be inserted into the sensor hole402after the ball valve is opened to expose the flow sensor100to the fluid within the pipe300. Optionally, the sensor hole402can be formed on other pipe elements in the pipe system, including but not limited to valves, elbows, joints, hydrants, and meters, and, as one skilled in the art will appreciate, the flow sensor100can thereby be installed on any of these pipe elements in various other aspects.

In a further aspect, the pipe wall saddle310can be mounted to the exterior surface301of the pipe300by placing the neck312over the sensor hole402and tightening the fasteners307a,b, placing the first saddle segment305and the second saddle segment306into sealing engagement with the exterior surface301. It is also contemplated that the external member110of the flow sensor100can then be inserted into the sensor hole402and coupled to the pipe wall saddle310such that a portion of the external member110extends into the interior400of the pipe300, thereby placing the portion of external member in the operative positon across a flow path of fluid within the pipe system. In this aspect, the flow sensor100can be coupled to the pipe wall saddle310by engaging the external threading on the hex bushing122with the complementary internal threading of the saddle hex bushing311.

In yet another aspect, a measuring device, such as a voltmeter or any other device configured to measure a charge or a voltage, can be operably and/or electrically coupled to the RCA connector140. Thus, as fluid flows across the external member110, the external member110, tube210, and piezoelectric cable200can vibrate as a result of the impact of the fluid flowing in the pipe and impacting the external surface of the external member110. The vibrations sympathetically flexes the piezoelectric material layer500in the piezoelectric cable200, which causes the piezoelectric material layer500to generate a voltage due to the piezoelectric effect. The voltage is transmitted through the piezoelectric cable200to the RCA connector140and then to the measuring devices, thereby measuring a voltage output of the flow sensor100. In other aspects, the measuring device can measure a charge output from the piezoelectric material layer500. Optionally, the stiffening sleeve130can be configured to prevent flexure of the portion of the piezoelectric cable200between the RCA connector140and the mounting adapter120during use of the flow sensor100, thereby preventing interruptions in the output of the piezoelectric material layer500.

In a further aspect, by measuring an output from piezoelectric cable200, the flow sensor100is capable of detecting a change in flow of the fluid in the pipe300. For example, during a pipe burst situation either downstream or upstream of the flow sensor100, the rate of fluid flow in the pipe changes. In this instance, the vibration frequency of the flow sensor100would change to a different frequency as a result of the change in the fluid flow, which would cause a change in output from the piezoelectric cable200, which can be detected by the measuring device. In this aspect, the change in output can trigger a warning or alert in the measuring device, which, optionally, can be communicated to monitoring system, or the measuring device can communicate the voltage or charge output to the monitoring system to monitor the output and generate the warning or alert. In various aspects, the warning or alert can be in the form of a siren, light, text or email message, or any other communication that indicates a change in flow or a possible pipe burst. In various aspects, multiple flow sensors100can be utilized, with at least one flow sensor100detecting acoustics within the pipe system and at least one flow sensor100detecting flow rates, which can then be compared to detect and confirm a burst or leak. In various aspects, multiple flow sensors100can be utilized to determine a location of a burst or leak by cross-correlating the sensor outputs.

In a further aspect, the charge or voltage output from the flow sensor100can be used to monitor an approximate flow rate of the fluid in the pipe300. In this aspect, it is contemplated that the output can be correlated to specific flow rates based on the dimensions and other characteristics of the flow sensor100, the size and material of the pipe, the type and temperature of the fluid, and any other factors affecting the relationship between the output and the fluid flow rate.

In another aspect, the external member110can be a housing for the tube210and the piezoelectric cable200. In an exemplary aspect, the external member110can comprise brass or other like materials suitable for use in potable water, which allows the flow sensor100to be used in a potable water distribution system. One skilled in the art will also appreciate that the flow sensor100also requires little to no power during use, as the signal is generated by the inherent properties of the piezoelectric cable200.

In one aspect, it is contemplated that flow sensor100can be configured without use of the external member110. In this aspect, the tube210can be a housing for the piezoelectric cable200that can be then be inserted into the flow path.

It should be emphasized that the above-described aspects are merely possible examples of implementations, merely set forth for a clear understanding of the principles of the present disclosure. Many variations and modifications can be made to the above-described embodiment(s) without departing substantially from the spirit and principles of the present disclosure. All such modifications and variations are intended to be included herein within the scope of the present disclosure, and all possible claims to individual aspects or combinations of elements or steps are intended to be supported by the present disclosure. Moreover, although specific terms are employed herein, as well as in the claims which follow, they are used only in a generic and descriptive sense, and not for the purposes of limiting the described invention, nor the claims which follow.