Patent Description:
Flow rates of fluids, gas, and loose solids are a measure of interest in plumbed, pumped, piped and channelized flow streams. In some plumbing systems, these flow streams may stretch over great distance and monitoring of the plumbing subsections can become difficult. Furthermore, these flow streams may comprise different flow rates across a cross section of the flow streams. Some areas of the flow stream may comprise homogeneous turbulent flow and other areas of the flow stream may comprise non-homogeneous turbulent flow. Conventional fluid flow sensors require extended linear channels or straight pipes to accurately measuring flow rate. Moreover, conventional mechanical fluid flow sensors typically only cover a portion of a cross-section of the flow stream so as not to affect the velocity of the flow stream. Therefore, a measurement of fluid velocity may not include turbulent portions of the flow stream, or a portion of the flow stream near the channel or pipe walls. The relationship between the flow stream velocity and movement of the fluid flow sensor are also not linear. Therefore, as the flow stream velocity increases, the accuracy of conventional mechanical fluid flow sensors significantly decreases. <CIT> discloses a vane type flowmeter from the prior art, comprising an obstruction member moved by the flowing fluid, three cams, a spring and an arcuate appendage. The obstruction member rotates about a bowl linked to the first cam.

In some configurations, a fluid flow sensor adapted for measuring a fluid velocity over a range of fluid velocities may include: a plurality of cams; an obstruction member coupled to a first cam in the plurality of cams, wherein the obstruction member may be configured to rotate about the first cam relative to the fluid velocity; an arcuate appendage coupled to a second cam in the plurality of cams, wherein the arcuate appendage may be configured to rotate about the second cam; and a torsion spring coupled at least one of the plurality of cams, wherein the plurality of cams may be configured to convert a rotation of the obstruction member into a rotation of the arcuate appendage, and wherein the plurality of cams and the torsion spring may be configured to linearize a rotation of the arcuate appendage over the range of fluid velocities.

In some configurations, the fluid flow sensor, may include a second obstruction member coupled to the first cam, wherein the second obstruction member may be configured to rotate about the first cam relative to the fluid velocity, and wherein the plurality of cams may be configured to convert a rotation of the second obstruction member into a rotation of the arcuate appendage.

In some configurations, the fluid flow sensor, the plurality of cams may each include a cam profile.

In some configurations, the plurality of cams may each include a same cam profile.

In some configurations, the plurality of cams may each include a different cam profile.

In some configurations, the fluid flow sensor adapted for measuring a fluid velocity over a range of fluid velocities may include: an obstruction assembly including an obstruction member coupled to a first cam, wherein the obstruction member may be rotatable about the first cam; an indicator assembly including a torsion spring, a second cam and an arcuate appendage, wherein the arcuate appendage may be coupled to the second cam, and the torsion spring may provide a rotational force on the second cam, and wherein the arcuate appendage may be rotatable about the second cam; a linkage configured to couple the first cam to the second cam so the indicator assembly rotates when the obstruction assembly rotates; and an indicator lid, the indicator lid having an arcuate configuration forming an arcuate protruding upper portion, and includes a rim and a receiver pocket adapted for receiving at least a portion of the arcuate appendage, wherein when the arcuate appendage rotates, the arcuate appendage moves in an arcuate path inside the indicator lid, wherein the first cam may include a first cam profile, and the second cam may include a second cam profile, and wherein the first cam profile, the second cam profile, and the torsion spring may be configured to linearize a rotation of the arcuate appendage over the range of fluid velocities.

In some configurations, the first cam profile and the second cam profile may include a same profile.

In some configurations, the first cam profile and the second cam profile may include a different profile.

In some configurations, the torsion spring may include a non-linear spring.

In some configurations, the techniques described herein relate to a fluid flow sensor, wherein the torsion spring may include a linear spring.

In some configurations, the fluid flow sensor may include an array of magnetic sensors coupled to the indicator lid, and a magnet coupled to the arcuate appendage, wherein the array of magnetic sensors may convert a physical position of the magnet into a digital reading of the fluid velocity.

In some configurations, the fluid flow sensor may include an antenna configured to transmit the digital reading to an external device.

In some configurations, a physical position of the arcuate appendage inside the indicator lid may relate to the fluid velocity, and the fluid velocity may be indicated visually against a scale imprinted on the indicator lid.

In some configurations, the fluid flow sensor may be coupled to a display.

In some configurations, the display may be configured to display a turnover rate.

In some configurations, the fluid flow sensor adapted for measuring a fluid velocity over a range of fluid velocities may include: an obstruction assembly including a plurality of obstruction members coupled to a first cam, wherein the plurality of obstruction members may be rotatable about the first cam; an indicator assembly including a torsion spring, a second cam and an arcuate appendage, wherein the arcuate appendage may be coupled to the second cam, and the torsion spring provides a rotational force on the second cam, and wherein the arcuate appendage is rotatable about the second cam; a linkage configured to couple the first cam to the second cam so the indicator assembly rotates when the obstruction assembly rotates; and an indicator lid, the indicator lid having an arcuate configuration forming an arcuate protruding upper portion, and includes a rim and a receiver pocket adapted for receiving at least a portion of the arcuate appendage, wherein when the arcuate appendage rotates, the arcuate appendage moves in an arcuate path inside the indicator lid, wherein the first cam includes a first cam profile, and the second cam includes a second cam profile, and wherein the first cam profile, the second cam profile, and the torsion spring are configured to linearize a rotation of the arcuate appendage over the range of fluid velocities.

In some configurations, the fluid flow sensor may be coupled to a pipe.

In some configurations, the fluid flow sensor may be coupled to the pipe with a saddle clamp.

In some configurations, a cross-section of the pipe may include a plurality of zones, and each of the plurality of obstruction members may be configured to obstruct a fluid flow in different zones.

These and other features, aspects, and advantages of the present disclosure are described with reference to the drawings of certain embodiments, which are intended to schematically illustrate certain embodiments and not to limit the disclosure.

As described above, conventional fluid flow sensors require extended linear channels or straight pipes to accurately measuring flow rate. Moreover, conventional mechanical fluid flow sensors typically only cover a portion of a cross-section of the flow stream so as not to affect the velocity of the flow stream. Therefore, a measurement of fluid velocity may not include turbulent portions of the flow stream, or a portion of the flow stream near the channel or pipe walls. The relationship between the flow stream velocity and movement of the fluid flow sensor are also not linear. Therefore, as the flow stream velocity increases, the accuracy of conventional mechanical fluid flow sensors significantly decreases. Accordingly, there is a need for an improved fluid flow sensor that can measure the flow velocity of turbulent flows and linearize the relationship between flow stream velocity and the movement of the fluid flow sensor.

The present disclosure provides examples of an improved fluid flow sensor configured to linearize a rotation of an obstruction over a range of fluid velocities. The fluid flow sensor may also include an obstruction that improves accuracy of the fluid flow sensor.

<FIG> and <FIG> illustrate an example of a fluid flow sensor <NUM>. The fluid flow sensor may include an obstruction member <NUM> (which may be a part of an obstruction assembly), a first cam <NUM>, a second cam <NUM>, an arcuate appendage <NUM>, an indicator lid <NUM>, a body <NUM>, a first linkage <NUM>, and a second linkage <NUM>. The indicator lid <NUM> may be coupled to a top <NUM> of the body <NUM>. The body <NUM> may include sidewalls <NUM>. The first cam <NUM> may be rotatably coupled to the sidewalls <NUM> substantially near a bottom <NUM> of the body <NUM>. The first cam <NUM> may be rotatably coupled to the body <NUM> by a first rotatable shaft <NUM>. The obstruction member <NUM> may be coupled to a distal end <NUM> of the first cam <NUM> such that when a force or pressure is applied to the obstruction member <NUM>, for example, a fluid flow, the obstruction member <NUM> and the first cam <NUM> rotate about the first rotatable shaft <NUM>. In this way, the larger the force or pressure applied to obstruction member <NUM>, the more the obstruction member <NUM> and the first cam <NUM> rotate about the first rotatable shaft <NUM>. In some embodiments, an angle of rotation of the obstruction member <NUM> may depend on the pressure applied to the obstruction member <NUM>.

In some embodiments, the second cam <NUM> may be rotatably coupled to the sidewalls <NUM> by a second rotatable shaft <NUM>, substantially near the top <NUM> of the body <NUM>. In some embodiments, the second cam <NUM> may be rotatably coupled to the body <NUM> anywhere on sidewalls <NUM> between the first cam <NUM> and the top <NUM> of the body <NUM>. The second cam <NUM> may be coupled to the first cam <NUM> via a first linkage <NUM>. The first linkage <NUM> may be a wire, a chain, a cable, or any other flexible linkage. The first linkage <NUM> may apply a rotational force to the second cam <NUM>. In this way, when the first cam <NUM> rotates around the first rotatable shaft <NUM>, the first cam <NUM> may pull on the first linkage <NUM>, and the first linkage <NUM> may pull on the second cam <NUM>, thereby rotating the second cam <NUM>.

In some embodiments, fluid flow sensor <NUM> may include a spring <NUM> coupled to the second cam <NUM> (both of which, in addition to the arcuate appendage <NUM>, may form an indicator assembly). The spring <NUM> may be a torsional spring (e.g., also referred to herein as a torsion spring), a tension spring, or a compression spring configured to provide a rotational force on the second cam <NUM>. The spring <NUM> may be coupled to the second cam <NUM> such that when the second cam <NUM> rotates around the second rotatable shaft <NUM>, the spring <NUM> provides a rotational force on the second cam <NUM>. The rotational force provided by the spring <NUM> may counteract the rotation of the obstruction member <NUM>, the first cam <NUM>, and the second cam <NUM>. In this way, when a force is applied to the obstruction member <NUM> by a fluid flow, the spring <NUM> will provide an opposing rotational force. In some embodiments, the spring <NUM> may be preloaded such that the obstruction member <NUM>, the first cam <NUM>, and the second cam <NUM> may not rotate until the fluid flow applies a force on the obstruction member <NUM> larger than the force applied by the spring <NUM>. By preloading the spring <NUM>, a minimum fluid velocity of the range of fluid velocities detected by the fluid flow sensor <NUM> may be adjusted. In some embodiments, the spring <NUM> may be coupled to the first cam <NUM>.

In some embodiments, the fluid flow sensor may include multiple springs <NUM>. In these embodiments, the multiple springs <NUM> may each be coupled to the second cam <NUM> in parallel or in series. In some embodiments, the multiple springs <NUM> may be coupled to the first cam <NUM>. In some embodiments, one or more of the multiple springs <NUM> may be coupled to the first cam <NUM>, and one or more of the multiple springs may be coupled to the second cam <NUM>. In some embodiments, the multiple springs <NUM> may apply a force in the same direction. In some embodiments, the multiple springs <NUM> may apply a force in opposing directions.

In some embodiments, the second cam <NUM> may be coupled to an arcuate appendage <NUM>. The arcuate appendage <NUM> may be coupled to the second cam <NUM> such that the arcuate appendage <NUM> rotates about the second rotatable shaft <NUM>. The arcuate appendage <NUM> may be coupled to the second cam <NUM>, or the arcuate appendage <NUM> may be coupled directly to the second rotatable shaft <NUM>. The arcuate appendage <NUM> may include a protruding portion <NUM>. The protruding portion <NUM> may extend from the second cam <NUM> out of the top <NUM> of the body <NUM>. The protruding portion <NUM> may extend into the indicator lid <NUM>. The protruding portion <NUM> may be configured such that as the fluid flow velocity increases, and the obstruction member <NUM> rotates, the protruding portion <NUM> may rotate about the second rotatable shaft <NUM> and further extends into the indicator lid <NUM>.

In some embodiments, the fluid flow sensor <NUM> may include a second linkage <NUM>. The second linkage may be coupled to the first cam <NUM> and the second cam <NUM>, or the second linkage <NUM> may be coupled to the arcuate appendage <NUM> and the obstruction member <NUM>. As shown in <FIG> and <FIG>, the obstruction member <NUM> and the first cam <NUM> may rotate counterclockwise about the first rotatable shaft <NUM> as the fluid flow increases from left to right. As described above, the first linkage <NUM> may rotate both the second cam <NUM> and the arcuate appendage <NUM> counterclockwise about the second rotatable shaft <NUM> as the fluid flow increases. However, since the first linkage <NUM> may comprise a wire, a chain, a cable, or any other flexible linkage, the first linkage <NUM> may be unable transfer a rotational force applied by the spring <NUM> to the obstruction member <NUM> and the first cam <NUM>. The second linkage <NUM> may be configured to transfer the rotational force applied by the spring <NUM> to the obstruction member <NUM> and the first cam <NUM>.

In some embodiments, the first cam <NUM> and the second cam <NUM> may each comprise a cam profile. In some embodiments, the cam profiles of the first cam <NUM> and the second cam <NUM> may be circular. In some embodiments, the cam profiles may be elliptical or any other non-circular cam profile. Both the first cam <NUM> and the second cam <NUM> may comprise the same cam profile, or the first cam <NUM> and the second cam <NUM> may comprise different cam profiles. Cam profiles may be selected depending on a preferred flow velocity range, or rotational profile of the arcuate appendage <NUM>.

In some embodiments, the cam profiles of the first cam <NUM> and the second cam <NUM> may be selected to alter the rotation of the obstruction member <NUM> and the arcuate appendage <NUM> relative to the fluid flow velocity. Different cam profiles may alter how much the obstruction member <NUM> and the arcuate appendage <NUM> rotate relative to each other.

In some embodiments, characteristics of the spring <NUM> may be selected to change the counter force provided by the spring <NUM>. For example, a characteristic of the spring <NUM> may comprise a material, and depending on the material, the spring may provide a different counter force. A size and shape of the spring may also affect the counter force applied by the spring <NUM>. In some embodiments, the spring <NUM> may be a liner spring or a non-linear spring. The material, the size, and the shape of the spring <NUM> may be selected depending on a preferred flow velocity range, a rotational profile of the arcuate appendage <NUM>, and/or a rotational profile of the obstruction member <NUM>.

In some embodiments, the cam profiles of the first cam <NUM> and the second cam <NUM>, and the spring <NUM> may be configured to linearize the rotation of the arcuate appendage <NUM> over the preferred flow velocity range. In this way, as the fluid velocity increases linearly, an angle of rotation of the arcuate appendage <NUM> about the second rotatable shaft <NUM> may increase linearly. As an illustrative example, if the fluid velocity increases from <NUM> ft/s to <NUM> ft/s, the arcuate appendage <NUM> may rotate <NUM> degrees about the second rotatable shaft <NUM>, and if the fluid velocity increases from <NUM> ft/s to <NUM> ft/s, the arcuate appendage <NUM> may again rotate <NUM> degrees about the second rotatable shaft <NUM>. In some embodiments, the cam profiles of the first cam <NUM> and the second cam <NUM>, and the spring <NUM> may be configured to linearize the rotation of the obstruction member <NUM> over the preferred flow velocity range. In this way, as the fluid velocity increases linearly, an angle of rotation of the obstruction member <NUM> about the first rotatable shaft <NUM> may increase linearly. For example, if the fluid velocity increases from <NUM> ft/s to <NUM> ft/s, the obstruction member <NUM> may rotate <NUM> degrees about the first rotatable shaft <NUM>, and if the fluid velocity increases from <NUM> ft/s to <NUM> ft/s, the obstruction member <NUM> may again rotate <NUM> degrees about the second rotatable shaft <NUM>. In any of these embodiments, a linear relationship between a change in fluid velocity and the rotation of the obstruction member <NUM> or the arcuate appendage <NUM> may increase the accuracy of the fluid flow sensor <NUM>. Without a linear relationship, as the obstruction member <NUM> rotates about the first rotatable shaft, the obstruction member <NUM> may rotate less for the same change in fluid flow velocity. Therefore, detecting a small change in fluid flow velocity may be more difficult.

In some embodiments, as described above, the protruding portion <NUM> of the arcuate appendage <NUM> may extend into indicator lid <NUM>. The indicator lid <NUM> may include an arcuate portion <NUM> (also referred to herein as an arcuate protruding upper portion <NUM>) and a connector portion <NUM>. The arcuate portion <NUM> may include a receiving pocket <NUM> with an arcuate configuration such that as the protruding portion <NUM> extends into the receiving pocket <NUM>, the protruding portion <NUM> follows the same path as a top surface <NUM> of the receiving pocket <NUM>. In some embodiments, the connector portion <NUM> may be rotatably coupled to the second rotatable shaft <NUM>. In this way, a user may rotate the indicator lid <NUM> about the second rotatable shaft <NUM> in order to access an interior of the fluid flow sensor <NUM>.

In some embodiments, the fluid flow sensor <NUM> may include acrylonitrile butadiene styrene (ABS), polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC), polycarbonate, stainless steel, aluminum, copper, brass, bronze, and/or any other corrosion resistant material.

<FIG> illustrates an example of an indicator lid <NUM>. As described above, the indicator lid <NUM> may include an arcuate portion <NUM> and a connector portion <NUM>. The connector portion <NUM> may include a rim <NUM> with a plurality of holes <NUM>. The plurality of holes <NUM> may be configured to receive a screw or other mechanical fastener in order to couple the indicator lid <NUM> and the fluid flow sensor <NUM> to a pipe, a channel, or other mechanism for transporting fluid. In some embodiments, the fluid flow sensor <NUM> may be coupled to a saddle clamp, and the saddle clamp may couple the fluid flow sensor <NUM> to the pipe or other mechanism for transporting fluid. The fluid flow sensor <NUM> may be coupled to a pipe such that the indicator lid <NUM> is outside of the pipe, and the obstruction member <NUM> is in the pipe, as further described below with reference to <FIG>.

In some embodiments, the arcuate portion <NUM> may include a scale <NUM> for visually indicating the fluid flow velocity. The scale <NUM> may be printed or imprinted on the top surface <NUM>. In some embodiments, the scale <NUM> is printed or imprinted on an inside of the top surface <NUM>. In some embodiments, the scale <NUM> is printed or imprinted on the outside of the top surface <NUM>. The scale <NUM> may be substantially the same size and shape as the top surface <NUM>. In some embodiments, the scale <NUM> may include a slot <NUM>. The slot <NUM> may be a portion of the scale <NUM> that is substantially see-through or transparent. The slot <NUM> may extend from a bottom <NUM> of the scale <NUM> to a top <NUM> of the scale. The slot <NUM> may allow a user to see the protruding portion <NUM> through the scale <NUM> and the top surface <NUM>. In some embodiments, the scale <NUM> may include indicators <NUM>. In some embodiments, the indicators <NUM> may correspond to a position of the protruding portion <NUM>. The indicators <NUM> may relate a position of the protruding portion <NUM> to a fluid flow velocity. The indicators <NUM> may be printed on a portion of the scale <NUM> next to the slot <NUM>, and the indicators <NUM> may be on either side of the slot <NUM>. In this way, when a user looks through the slot <NUM> at a position of the protruding portion <NUM>, the indicators <NUM> show a user to what fluid flow velocity the position of the protruding portion <NUM> relates. The indicators <NUM> on either side of the slot may include different units of measurement. For example, the indicators <NUM> to the right of the slot <NUM> may have units of ft/s, and the indicators <NUM> to the left of the slot <NUM> may have units of m/s. In some embodiments, the scale <NUM> may include any units of velocity or volumetric flow rate or any combination thereof.

In some embodiments, the top surface <NUM> may be substantially optically clear to allow a user to see the scale <NUM> and the protruding portion <NUM>. In some embodiments, substantially the whole indicator lid <NUM> may be substantially optically clear.

In some embodiments, as shown in <FIG>, the indicator lid may include one or more magnetic field sensors <NUM> (where the magnetic field sensors <NUM> may be referred to as an array of magnetic field sensors <NUM> if a plurality are present). The magnetic field sensor(s) <NUM> may be located on the arcuate portion <NUM> of the indicator lid <NUM>. In these embodiments, the protruding portion <NUM> may include a magnet <NUM>. As the protruding portion <NUM> and the magnet <NUM> physically move into the receiving pocket <NUM>, the magnet <NUM> changes the magnetic field strength and direction of magnetic field lines of force relative to the magnetic field sensor(s) <NUM>, which in turn changes the strength and orientation of the magnetic field and the alignment of the magnetic lines of force. The change in the strength and orientation of the magnetic field allows for the magnetic field sensor(s) <NUM> to detect a velocity by electromagnetic field detection methods. For example, the magnetic field sensor(s) <NUM> may be Hall Effect sensors. By using Hall effect sensors, fluid velocity may be measured by both strength of the magnetic field and the orientation of the magnetic field. As the arcuate appendage <NUM> rotates about the second rotatable shaft <NUM>, so does the magnet <NUM> and the magnetic field. The magnetic field sensor(s) <NUM> may convert a physical position of the protruding portion <NUM> into an electrical signal. In some embodiments, the indicator lid <NUM> may include an optical sensor instead of magnetic field sensor(s) <NUM> in order to convert the physical position of the protruding portion <NUM> to an electrical signal.

In some embodiments, the fluid flow sensor <NUM> may communicate with an external device, such as a mobile computing device, or a digital indicator <NUM>, as shown in <FIG>. The digital indicator <NUM> may include a housing <NUM> and a screen <NUM>. The screen <NUM> may be coupled to the housing <NUM>. In some embodiments, the fluid flow sensor <NUM> may include wiring and/or an antenna configured to transmit the electrical signal to an external device. In these embodiments, the digital indicator <NUM> may include inputs <NUM>. The inputs <NUM> may include a plug for wiring and/or a receiver (or transceiver). The wiring of the fluid flow sensor <NUM> may be coupled to the plug in order to transfer the electrical signal of the physical position of the protruding portion <NUM> to the digital indicator <NUM>. Alternatively, the antenna of the fluid flow sensor <NUM> may communicate wirelessly with the receiver of the digital indicator <NUM> in order to transfer the electrical signal of the physical position of the protruding portion <NUM> to the digital indicator <NUM>. The digital indicator <NUM> may include a processor (not shown) configured to convert the electrical signal received from the fluid flow sensor <NUM> into display information for the screen <NUM>.

In some embodiments, the screen <NUM> may display information associated with the fluid flow. In some embodiments, the screen <NUM> may display a digital arcuate indicator <NUM>. The digital arcuate indicator <NUM> may display the fluid flow velocity or volumetric flow rate. The digital arcuate indicator <NUM> may be a digital representation of the scale <NUM>. In some embodiments, the screen <NUM> may display a fluid flow velocity number <NUM>. The fluid flow velocity number <NUM> may include units of gallons per minute, gallons per second, liters per minute, liters per second, feet per second, meters per second, or any other velocity or volumetric flow rate. In some embodiments, the fluid flow velocity number <NUM> may correspond to the fluid flow velocity displayed on the digital arcuate indicator <NUM>, or the fluid flow velocity number <NUM> may be an average fluid flow velocity over a period of time. The period of time may include <NUM> second, <NUM> seconds, <NUM> seconds, <NUM> seconds, <NUM> seconds, <NUM> seconds, <NUM> minute, <NUM> minutes, <NUM> minutes, <NUM> minutes, <NUM> hour, <NUM> hours, <NUM> hours, or any other period of time.

In some embodiments, the screen <NUM> may display a turnover rate (TOR) <NUM>. In some embodiments, the TOR <NUM> may be the number of times an entire volume of fluid in a system passes through the system in a certain period of time. For example, the entire volume of fluid may pass through the system two and a half times time per hour, and the screen <NUM> may display the TOR <NUM> as <NUM>. In some embodiments, the TOR <NUM> may be a time for the entire volume of fluid in the system to pass through the system. For example, the entire volume of fluid may pass through the system in an hour and a half, and the screen <NUM> may display the TOR as <NUM>. In some embodiments, the volume of fluid in the system may be input by a user. In these embodiments, the fluid flow sensor <NUM> and/or the digital indicator may include a memory to store an input volume of fluid in the system. In some embodiments, the screen <NUM> may display the digital arcuate indicator <NUM>, the fluid flow velocity number <NUM> and the TOR <NUM>. Although the screen <NUM> is described in various embodiments as displaying the digital arcuate indicator <NUM>, the fluid flow velocity number <NUM> and/or the TOR <NUM>, the screen <NUM> may display any information associated with the fluid flow velocity without deviating from the scope of the present application.

In some embodiments, the digital indicator <NUM> may be coupled to the indicator lid <NUM>, or on a pipe near the fluid flow sensor <NUM>. In the embodiments where the digital indicator is coupled to the indicator lid <NUM>, the digital indicator <NUM> may not have a housing. In these embodiments, the screen <NUM> may be coupled to the indicator lid <NUM>.

In some embodiments, the fluid flow sensor <NUM> and/or the digital indicator <NUM> may include an alarm. The alarm may be coupled to the indicator lid <NUM> or the housing <NUM>. In some embodiments, the alarm may notify the user if the flow rate is greater than a maximum flow rate. The maximum flow rate may be determined by municipal code or input by the user. In some embodiments, the alarm may notify the user if the flow rate is less than a minimum flow rate. The minimum flow rate may be determined by municipal code and optionally pre-coded or input by the user. In some embodiments, the alarm may notify the user if the flow rate is zero. In any of the embodiments with the alarm, the alarm may alert the user that something is wrong with the system, or the fluid flow sensor <NUM>, such as an operating error, a malfunction, a power loss, etc..

<FIG> illustrates an example of the fluid flow sensor <NUM> coupled to a pipe <NUM>. As described above, the indicator lid <NUM> may include a plurality of holes <NUM> configured to receive a screw or other mechanical fastener in order to couple the fluid flow sensor <NUM> to a pipe or other mechanism for transporting fluid. As shown in <FIG> and described above in reference to <FIG> and <FIG>, the fluid flow sensor <NUM> may be coupled to a pipe such that the indicator lid <NUM> is outside of the pipe, and substantially the rest of the fluid flow sensor <NUM> from the top <NUM> of the body <NUM> may be inserted through a hole <NUM> in the pipe and disposed inside of the pipe <NUM>. Any amount of the fluid flow sensor <NUM> may be disposed inside of the pipe, as long as at least a portion of the obstruction member <NUM> is inside the pipe <NUM>. In this way, the scale <NUM> may be read by a user when the fluid flow sensor <NUM> is coupled to a pipe <NUM>. In some embodiments, the fluid flow sensor is built into the pipe <NUM>. In these embodiments, ends of the pipe <NUM> may be coupled to portions of a pipe already part of a system of pipes. In other embodiments, the fluid flow sensor <NUM> may be coupled to an existing pipe with a saddle clamp.

<FIG> shows a cross-section of the pipe <NUM>. As shown in <FIG>, the pipe <NUM> may be split into a number of areas <NUM>. In one embodiment, the pipe <NUM> is split into nine areas <NUM> labelled A<NUM>-A<NUM>. Depending on the fluid, a size of the pipe <NUM>, a shape of the pipe <NUM>, a material of the pipe <NUM>, an elevation of the pipe <NUM>, an angle of the pipe <NUM>, or other characteristics of the pipe <NUM>, a flow in the different areas <NUM> may have different velocities. For example, due to friction from an inner surface of the pipe, fluid travelling through areas A<NUM>, A<NUM>, A<NUM>, A<NUM>, A<NUM>, A<NUM>, A<NUM>, and A<NUM> may have a lower velocity than fluid travelling through area As. In some areas <NUM> of the pipe <NUM>, the flow may be substantially laminar, and in other areas <NUM> of the pipe <NUM> the flow may be turbulent.

Since velocities and flow types may vary across different areas <NUM> of the pipe <NUM>, an alternative obstruction member <NUM>, shown in <FIG>, may provide more accurate measurements of flow velocity. The obstruction member <NUM> may include one or more extensions <NUM>, and one or more obstructions <NUM>. The extension(s) <NUM> may each include a proximal end <NUM> and a distal end <NUM>. The proximal end <NUM> of an extension <NUM> may be coupled to the distal end <NUM> of the first cam <NUM>. An obstruction <NUM> may be coupled to a distal end <NUM> of an extensions <NUM>. The obstruction member <NUM> may be configured such that the obstruction(s) <NUM> are disposed in different areas <NUM> of the pipe <NUM>. In this way, the obstruction member <NUM> covers more areas <NUM> than the obstruction member <NUM>. Although the force acting on each obstruction <NUM> may be different due to a differing fluid flow velocity in different areas <NUM> of the pipe <NUM>, an angle of rotation of the obstruction member <NUM> may be a function of a force applied over an area of the obstruction member <NUM>. Therefore, the rotation of the obstruction member <NUM> relates to an average velocity of the fluid in the pipe <NUM>. The obstruction member <NUM> with a plurality of obstructions <NUM> in different areas <NUM> of the pipe <NUM> may provide a more accurate measurement of the average fluid flow in the pipe <NUM>. While <FIG> depicts the obstruction member <NUM> as including five extensions <NUM> and obstructions <NUM> being present, this is not meant to be limiting. The obstruction member <NUM> can include any number of extensions <NUM> and/or obstructions <NUM>.

Claim 1:
A fluid flow sensor (<NUM>) adapted for measuring a fluid velocity over a range of fluid velocities, comprising:
a plurality of cams (<NUM>, <NUM>);
an obstruction member (<NUM>) coupled to a first cam in the plurality of cams;
an arcuate appendage (<NUM>) coupled to a second cam in the plurality of cams, wherein the arcuate appendage is configured to rotate about the second cam; and
a spring (<NUM>) coupled to at least one of the plurality of cams,
wherein the plurality of cams is configured to convert a rotation of the obstruction member into a rotation of the arcuate appendage, and wherein the plurality of cams and the torsion spring are configured to linearize a rotation of the arcuate appendage over the range of fluid velocities, characterized in that the obstruction member is rotatable about the first cam relative to the fluid velocity, and in that the spring is a torsion spring.