Oval gear meter

Embodiments include a flow measuring system for measuring characteristics of a fluid flow. The flow measuring system can include a pair of rotating members rotating synchronously to the fluid flow. At least one rotating member can include a normally-reflecting portion and a non-normally reflecting portion. The normally-reflecting portion reflects an incident beam in a direction parallel to the normal direction of the plane of the normally-reflecting portion. The non-normally reflecting portion reflects the incident beam in a direction non-parallel to the normal direction of the plane of the normally-reflecting portion. The flow measuring system measures the optical characteristics of a beam reflected by the normally-reflecting portion and determines rotational characteristics of the rotating member. The flow measuring system determines characteristics of the flow based on the rotational characteristics of the rotating member.

FIELD

This disclosure generally relates to systems and methods for measuring fluid flow. More specifically, the disclosure relates to an oval gear flow meter and methods of using the same.

BACKGROUND

Positive displacement fluid measurement systems can be used to measure a fluid flow rate or volume. For example, dispensing systems can use feedback from a positive displacement fluid meter to control the volume of fluid dispensed. Such control systems can be used in lieu of time-on controls to more accurately dispense precise amounts of fluid. An exemplary positive displacement fluid measurement system is an oval gear meter as described in U.S. Pat. No. 8,166,828; U.S. Pat. No. 8,069,719; and U.S. Pat. No. 7,523,660 each assigned to Ecolab Inc., St. Paul, Minn., the disclosure of each of which is hereby incorporated by reference in its entirety. A typical oval gear meter provides a pair of oval gears positioned within an oval gear chamber such that the gears rotate synchronously. In an oval gear meter, pockets are defined between the rotating oval gears and the inner chamber wall. Typically, fluid does not pass directly between the gears, and the volume of fluid exiting the chamber during each rotation is known. Conversely, the volume of fluid flow through a gear meter can be measured by measuring the number of rotations of the gears. Likewise, flow rate can be determined from the speed with which the gears rotate.

The rotational count and/or speed of rotation of gears can be measured in a number of different ways. For example, a timing gear system can be located external to the oval gear meter to measure the number of rotations of the oval gears and generate an appropriate signal representative of the volume flow rate of the fluid. Oval gear and other positive displacement flow meters utilizing timing gear systems usually have a gear chamber that includes one or more shaft apertures for the shafts coupling the gears to the external timing gears. In other cases, some gear meters instead use a non-contact sensor placed outside a substantially sealed chamber to determine gear rotation within the chamber. For example, non-contact magnetic sensors have been used to measure gear rotation.

Another example of a non-contact sensor is described in U.S. Pat. No. 7,523,660 assigned to Ecolab Inc., St. Paul, the disclosure of which is hereby incorporated by reference in its entirety. As the trigger gear rotates in response to fluid flow, the magnetic field generated by the permanent magnet also rotates. A magnetic sensor such as a GMR sensor (giant magneto resistance effect sensor) senses rotation of the magnetic field and generates an output signal representative of gear rotation. When calibrated against known volume or volumetric flow rate, the rotational count or speed of rotation of the gears respectively, the gears meter can be useful for measuring flow characteristics. One or more GMR sensor elements may be used to monitor rotation of the trigger wheel.

SUMMARY OF THE INVENTION

Certain embodiments of the invention include a flow measuring system. The flow measuring system can include a pair of rotating members rotating synchronously in response to a fluid flow to be measured by the flow measuring system. At least one rotating member can include a normally-reflecting portion adapted to reflect an incident beam in a direction toward a detector. In some embodiments, the rotating member can reflect the beam in a direction parallel to the normal direction “N” of the plane of the normally-reflecting portion. At least one rotating member also includes a non-normally reflecting portion adapted to reflect the incident beam in a direction away from the detector. In certain embodiments, the non-normally reflecting portion can reflect the incident beam in a direction non-parallel to the normal direction “N” of the plane of the normally-reflecting portion. The flow measuring system can determine rotational characteristics of the rotating member based on the optical characteristics of a beam reflected by the normally-reflecting portion. The flow measuring system determines flow characteristics based on rotational characteristics of the rotating member.

In certain embodiments, the flow measuring system includes a housing fluidly coupled to a fluid inlet and a fluid outlet. The housing can define a passage for a flow of a fluid. A first rotating member and a second rotating member can be disposed in the housing. The second rotating member can intermesh with the first rotating member.

In some embodiments, a sensor is operatively connected to the housing, and is optically aligned with the normally-reflecting portion. The sensor can measure optical characteristics of a beam reflected by the normally-reflecting portion. The sensor can determine at least one of a rotational count indicative of a number of rotations of the first rotating member or second rotating member, and a speed of rotation of the first rotating member or second rotating member based on the optical characteristics of the beam reflected by the normally-reflecting portion.

In certain embodiments, the sensor of the flow measuring system includes an emitter and a detector. The emitter can emit electromagnetic radiation toward at least the normally-reflecting portion, and the detector can detect electromagnetic radiation reflected by the normally-reflecting portion. The detector can be oriented such that at least a surface of the detector is parallel to the plane of the normally-reflecting portion. The surface of the detector can intercept the electromagnetic radiation reflected by normally-reflecting portion.

In some embodiments, the non-normally reflecting portion comprises a plurality of grooves, each groove adapted to reflect the incident beam in a direction away from the detector. In some embodiments, the plurality of the grooves can reflect the incident beam in a direction non-parallel to the normal direction “N” of the plane of the normally-reflecting portion. Each of the plurality of grooves can have a triangular cross-section. Each of the plurality of grooves can have a groove angle defined by a first sloping surface and a second sloping surface of the groove. In certain embodiments, the groove angle is not equal to 90 degrees. A first beam of electromagnetic radiation can be incident on the first sloping surface of the groove. The first beam of electromagnetic radiation can be reflected by the first sloping surface toward the second sloping surface. The second sloping surface can reflect the first beam of electromagnetic radiation in a direction non-parallel to the normal direction “N” of plane of the normally-reflecting portion. In one embodiment, the grooves are disposed in a spiral pattern about an axis of the rotating member. In another embodiment, the grooves are disposed concentrically about an axis of the rotating member. In still another embodiment, the grooves are disposed radially about an axis of the rotating member.

DETAILED DESCRIPTION

The following detailed description is exemplary in nature and is not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the following description provides some practical illustrations for implementing exemplary embodiments of the present invention. Examples of constructions, materials, dimensions, and manufacturing processes are provided for selected elements, and all other elements employ that which is known to those of ordinary skill in the field of the invention. Those skilled in the art will recognize that many of the noted examples have a variety of suitable alternatives.

FIGS. 1-2show front elevation and back perspective views of a positive displacement flow meter10according to certain embodiments. The positive displacement flow meter10can be fluidly coupled to a fluid system (not shown) for measuring162various characteristics (e.g., volume, flow rate, flow direction, etc.) of a fluid flow. The positive displacement flow meter10can be used in conjunction with fluids such as detergents, sanitizers, biological fluids, etc. The positive displacement flow meter10can be used in fluid systems such as fluid dispensing systems, fluid flow regulating systems and the like. For instance, the positive displacement flow meter10can be used to measure volume, concentration and flow rate of cleaning solutions for cleaning and/or sanitizing various facilities (e.g., healthcare facilities, food and beverage industries, public facilities, institutions, and the like). In such cases, monitoring characteristics of the flow can prevent out-of-product conditions from occurring during a cleaning or sanitizing operation. In one embodiment, the positive displacement flow meter10can be an oval gear meter100, as illustrated inFIG. 3. The oval gear meter100can measure one or more characteristics of a fluid flow by allowing the fluid flow to displace one or more components of the oval gear meter100.

With continued reference toFIG. 3, the oval gear meter100has a housing102. The housing102can include one or more flow passages104,106in fluid communication with a fluid system. One or more flanges108may allow the oval gear meter100to be mounted on a support surface (e.g., a wall, not shown) via fasteners (e.g., screws, bolts and the like, not shown). As seen inFIG. 3, the housing102includes a base110in fluid communication with the flow passages of the fluid system. The base110can define a chamber112therein to house a pair of gears114,116. In certain embodiments, the chamber can have a chamber inlet118, and a chamber outlet120. In the embodiment illustrated inFIG. 3, fluid enters via the flow passage104, on to the chamber inlet118. The fluid exits via the chamber outlet120and the flow passage106.

A cover122is secured to the base110using a number of fasteners124(e.g., bolts and nuts, screws, etc.). The cover122can be removably connected to the base110using the fasteners124. Alternatively, the cover122may be fixedly connected or bonded permanently to the base110(e.g., via adhesives, plastic weld, etc.). As shown inFIG. 3, the cover122and the base110encapsulate a separation member126, thereby securing162the separation member126against the chamber, thus eliminating the need to directly fasten the separation member126to the base110with fasteners (e.g., screws, bolts, etc.). When positioned between the base110and the cover122, the separation member126forms a fluid tight seal (e.g., via seals128,130) and prevents fluids from contacting the cover122. Alternatively, the separation member126can be coupled to the base110with fasteners, adhesives, and the like. Two seals (e.g., elastomer O-rings)128,130abut interior and exterior surfaces of the separation member126, between the base110and the separation member126and the cover122and the separation member126, respectively, to further provide a fluid-tight seal. The separation member126can be accessed by an operator due to the removable coupling between the base110and the cover122for cleaning or replacing the separation member126. In some cases, one separation member126(e.g., acid resistant) can be removed and replaced it with another separation member126(e.g., alkali resistant) to make the oval gear meter100compatible with a variety of materials.

The separation member126can be made of materials such as glass, sapphire, borosilicate, polymethylpentene, polysulfone, polyetherimide, polypropylene, polycarbonate, polyester, PVC, acrylic glass, and the like. Additionally, the separation member126can be made from one or more materials that are biocompatible and/or sufficiently chemically inert to the fluids flowing through the chamber. For instance, if the fluid passing through the chamber includes chemicals of wide range of pH (acids, alkalis and organic substances), oxidizers, and other corrosive chemicals, the separation member126can be made from an inert material such as sapphire or borosilicate. Other materials known in the art may also be used. The separation member126can be made of the same material as the cover122. Alternatively, the separation member126can be made of a material different from the cover122. For instance, the cover122can be made of a moldable plastic material such as polymethylpentene, polysulfone, polyetherimide, polypropylene, polycarbonate, polyester, and/or PVC.

The separation member126can have properties suitable for use with a variety of fluids and operating conditions. For instance, the separation member126can be planar (e.g., sheet-like or plate-like) with a thickness of a few millimeters. In one example, the thickness of the separation member126can be less than about 15 millimeters. In another example, the thickness is between about 1 millimeter and about 2 millimeters. It can be appreciated that any other thicknesses can be used as appropriate. The separation member126can also have suitable mechanical properties (e.g., impact resistance, hardness, density etc.) and thermal properties (e.g., thermal conductivity, coefficient of thermal expansion etc.) suitable for use with a variety of fluids. As seen inFIG. 3, the oval gear meter100includes a first gear114and a second gear116. Alternatively, other positive displacement flow meters can include first and second rotational members adapted to rotate synchronously in response to a fluid flow. Characteristics such as total volume, flow rate, and flow direction can then be measured based rotation of the first and second gears114,116(or other rotational members) as the fluid passes through the chamber, entering162via the chamber inlet and leaving via the chamber outlet. In the illustrated embodiment, the first and second gears114,116are oval shaped (e.g., ellipsoid), having a first major axis132and a second major axis134. In alternate embodiments, the first and second gears114,116can have any shape (e.g., circular, dog-bone, lobe shaped, helical etc.). In the illustrated embodiment shown inFIG. 3, the first and second gears114,116include a plurality of gear teeth136peripherally located on the first and second gears114,116. The teeth136of the first and second gears114,116mesh with each other over a portion of the perimeters of the first and second gears114,116. The first and second gears114,116rotate synchronously due to the intermeshing gear teeth136, rotating about the first and second major axes. When a volume of fluid enters the chamber and impinges on the first and second gears114,116, the first and second gears114,116begin rotating. As the first and second gears114,116turn, they trap the volume of fluid in the chamber because of the proximity of the teeth136to the chamber walls. Because the chamber wall nearly abuts an outermost point on at least one gear tooth136, throughout their rotation, this volume of fluid is trapped between the chamber wall and the surface of the teeth136and swept from the chamber inlet118to the chamber outlet120. Moreover, because the first and second gears114,116intermesh with each other during rotational movement, no fluid passes between the first and second gears114,116.

In certain embodiments, the first and second gears114,116can be of materials such as molded polymers. Alternatively, or additionally, the first and second gears114,116can be of materials resistant to corrosive chemicals. For example, if the oval gear meter100is used to monitor flow characteristics of fluids such as concentrated detergents, sanitizers, rinse aids and the like, the first and second gears114,116can be made of molded or machined plastic such as Polyether Ether Ketone (PEEK) and/or ceramics. The first and second gears114,116can be made of other materials such as polymers or crystallized thermoplastics (e.g., Polyetheramides, Polyphenylene sulfide and the like) having desired durability, temperature tolerance characteristics, coefficient of thermal expansion, moisture absorption characteristics, and chemical inertness. Additionally, the first and second gears114,116can be made of biocompatible materials suitable for use in fluid systems involving biological fluids.

In certain exemplary embodiments, the first and second gears114,116may not include any gear teeth136and each of the first and second gears114,116may have a smooth outer surface in contact with each other. Such embodiments may be suitable for measuring162flow characteristics of fluids that have a viscosity capable of preventing slippage between the first and second gears114,116. Alternatively, the first and second gears114,116having intermeshing gears may be useful for measuring162flow characteristics of fluids having lower viscosity and/or higher lubricity fluids than fluids which prevent gear slippage.

Although not shown inFIGS. 1-3, the fluid system can include a non-contact sensor configured to detect movement of the first and second gears114,116. In an exemplary embodiment, the non-contact sensor can be positioned on or connected operatively to the cover122. Various types of non-contact sensors can be incorporated into the flow meter to detect the movement of the first and second gears114,116from outside the chamber. In some embodiments, the non-contact sensor is an optical sensor. An example of a non-contact optical sensor is described in U.S. Pat. No. 8,069,719, assigned to Ecolab Inc., St. Paul, Minn., the disclosure of which is hereby incorporated by reference in its entirety. The optical sensor can view an optical characteristic of either of the first and second gears114,116, and based upon the measured optical characteristic of the first or second gears114,116, characteristics such as fluid volume, flow rate, and/or flow direction can be determined. The optical sensor can be any sensor capable of detecting the optical characteristic of the first and/or second gears114,116used to determine the rotational position of the first and/or second gears114,116.

Non-contact optical sensors can be used to measure any optical characteristic such as reflectance or transmittance. In some embodiments, the sensor can measure reflectance. In such embodiments, the optical sensor can include an emitter for emitting electromagnetic radiation at one or more wavelengths and a detector for detecting reflected electromagnetic radiation from a portion of the first or second gear116. The emitter can be positioned to receive reflected electromagnetic radiation of all or a portion of the range of reflected wavelengths. The emitter can emit electromagnetic radiation of any wavelength such as Ultraviolet (UV), visible, infrared (IR) and other spectrum. In some embodiments, the emitter can be a laser source, one or more halogen lamps, fluorescent lamps, or light emitting diodes (LED) emitting visible radiation at a specific wavelength (e.g., at 550 nm, 632 nm, etc.). Alternatively, UV emitters (e.g., deuterium lamp) emitting ultraviolet radiation (e.g., at 285 nm) or IR sources (e.g., IR lasers, Xenon lamps etc.) emitting infrared radiation (e.g., at 920 nm, 940 nm etc.) can be used to emit electromagnetic radiation toward the first and second gears114,116. In some embodiments, the detector can be a phototransistor. However, any detector (e.g., IR camera, UV detector, photodiodes etc.) can be used to detect the reflected wavelength. Alternatively, the sensor can measure transmittance. In such embodiments, the optical sensor can include an emitter as described above and a detector for detecting transmitted electromagnetic radiation from a portion of the first or second gear116. The detector can be any of the detectors described above and known in the art. The emitter and detector can be arranged such that the emitter is positioned facing one side (e.g., front) of the first or second gear116, and the detector is positioned facing the opposite side of the first or second gear116. Alternate embodiments of the invention may measure other optical characteristics such as absorptance, scattering efficiency and the like in a similar manner e.g., by suitably orienting an emitter for emitting electromagnetic radiation toward a portion of the first and/or second gears114,116and a detector for measuring162the desired optical characteristic.

In some embodiments, the separation member126can be substantially transparent to at least a portion of the spectrum of the emitted and reflected electromagnetic radiation (e.g., 300-700 nm, 700-1100 nm, 1100-2500 nm, etc.). Alternatively, a portion of the separation member126may be substantially transparent to at least a portion of the spectrum of the emitted and reflected electromagnetic radiation. In certain embodiments, an optical filter (not shown) can limit background radiation from entering162the sensor and/or oval gear meter100. In some embodiments, the optical filter can be a thin film deposited on the cover122and/or the separation member126. Transmittance of the optical filter can be tuned in various spectral ranges to minimize background radiation from interfering162with the measurement of the desired optical characteristic.

The separation member126can be aligned with the optical filter, optical sensor, and the first and second gears114,116to provide the optical sensor with a view of at least part of the first and second gears114,116through a portion of the separation member126and/or optical filter. The separation member126and cover122may also be at least partially transparent to allow an operator to visually observe operation of the flow meter. In one example, the cover122and separation member126may be made of a material that transmits a sufficient amount of visible light such that the first and/or the second gears114,116are discernible through the cover122and the separation member126. In another example, the cover122and separation member126are substantially transparent to visible light such that the first and/or the second gears114,116are completely, or substantially completely visible through the cover122and the separation member126. Alternatively, the cover122and separation member126are partially transparent (e.g., translucent) to allow a person to at least discern movement of the first and/or the second gears114,116. In some embodiments best illustrated inFIG. 3, the separation member126can be positioned behind an optical aperture140. When positioned as such, a portion of the first and/or second gears114,116may be visible through the optical aperture140and the separation member126.

The optical characteristic can be measured from a portion of at least one of the first and second gears114,116. In one example, the optical characteristic can be measured from a first surface142of the first and/or second gears114,116. In this example, the first surface142may have an optical characteristic different in magnitude from the optical characteristic of the remainder of the first and/or second gears114,116. When the first surface142of the first and/or second gears114,116is in the field of view of the detector, the detector registers a signal representative of the reflectance of the first surface142of the first and/or second gears114,116. As the first and second gears114,116continue rotating, a second surface144may appear in the field of view of the detector. At this instance, the detector registers a signal representative of the reflectance of the second surface144of the first and/or second gears114,116. Based on the differences in the signal due to reflectance of the first surface142and the second surface144, the optical sensor may discern gear rotation.

As disclosed in U.S. Pat. No. 8,069,719, assigned to the assignee of the instant application, and as best illustrated inFIGS. 4-6, an insert146can be positioned on the first and/or second gears114,116to facilitate improved detection of gear rotation. The insert146provide the optical sensor with sufficient contrast to distinguish between the optical characteristics of the insert and other areas of the gear. As the inserts do not span 360 degrees, during a full rotation of the first and/or second gears114,116, the insert146may be visible via the separation member126and the optical aperture140for a discrete duration, rather than continuously during the rotation of the gears. Thus, by counting the number of instances when the insert146is visible, the gear rotation may be discerned. The insert146can be of any desired shape. In the embodiment illustrated inFIGS. 4-6, the insert is bean-shaped. In certain embodiments, the insert146is white, with the surface of the first and/or second gears114,116being black. Alternatively, the insert146can be black, with the surface of the first and/or second gears114,116being black. In the embodiments illustrated inFIGS. 4-6, the surface of the first and/or second gears114,116is black and the insert146is white. In such embodiments, the insert146can have optical characteristics (e.g., reflectance, transmittance, etc.) that are different from the first and/or second gears114,116, thereby allowing the sensor to discern from when the inserts146are in a field of view of the optical sensor. By measuring an optical characteristic of the insert146, the optical sensor registers “an insert count” corresponding to when the insert146is in the field of view of the optical sensor. The insert counts can be related to the number of rotations of the first and/or second gear114,116, thereby allowing the gear rotational count and/or speed of rotation can be measured.

The insert146and the first and/or second gears114,116may be manufactured separately, and the insert146can be press-fitted into the first and/or second gears114,116such that it is substantially flush with the surface of the first and/or second gears114,116. Alternatively, or additionally, the insert146can be formed by molding. In some embodiments best seen inFIG. 6, the insert146may be positioned between an inner ring “I” and an outer ring “O”. As shown inFIG. 6, each insert may abut against a portion of the inner ring “I” and the outer ring “O”. When positioned, the insert146may be seated snugly in the first and/or second gears114,116and substantially flush with the surface of the first and/or second gear114,116.

While not illustrated inFIGS. 4-6, the first and/or second gears114,116receive a beam of electromagnetic radiation from an emitter (e.g., an external visible, UV, or IR source). In some embodiments, the insert146may be configured for reflecting the beam to the detector. Referring back toFIG. 3, a portion of the first and/or second gears114,116may be visible via the separation member126and/or optical aperture140as described elsewhere herein. Other areas of the first and/or second gears114,116may redirect the incident electromagnetic radiation into other directions. As the first and second gears114,116rotate, for every instance when the insert146is in the field of view of the detector, the detector receives a reflected beam from the insert. At other instances when the insert146is not in the field of view of the detector, the detector receives scattered beams from other areas of the first and/or second gears114,116. Based on any differences between the signals due to reflection from the insert146and those due to scattering from other areas of the first and/or second gears114,116, the rotational count and/or speed of rotation of the first and/or second gears114,116can be measured.

In some cases, the signals due to reflection from the insert146may not have sufficient accuracy to measure certain types of flows. Alternatively, or additionally, the insert146may not be mounted flush with the surface of the first and/or second gears114,116, leading to unstable signals during gear rotation. Additionally, inserts may increase manufacturing costs. In certain embodiments, the insert146may be replaced by patterns machined on the surface of the first and/or second gears114,116.FIGS. 7A-13illustrate various views of an oval gear200suitable for use as the first or second gear116according to certain embodiments of the invention. While an oval gear200is illustrated inFIGS. 7A-13, it should be understood that the embodiments described with respect toFIGS. 7A-13can be used with rotating members of any positive displacement flow meter.

In the illustrated embodiments shown inFIGS. 7A-13, the insert146is replaced by one or more normally-reflecting portions150on the surface of the oval gear200positioned in apposition to a non-normally reflecting portion152. As used herein, normal reflection refers to a reflected ray reaching a detector202. In other words, if a beam of electromagnetic radiation is reflected toward a detector202, such reflection is referred to as a “normal” reflection. Alternatively, if a beam of electromagnetic radiation is reflected in a direction away from the detector202, such reflection is referred to as a non-normal reflection.FIGS. 7B and 7Cshow an emitter201and a detector202positioned in apposition to the oval gear200at different instances. Electromagnetic radiation from emitter201reaches the oval gear200at the normally-reflecting portion150. The beam reflected by the normally-reflecting portion150is directed towards the detector202. In certain embodiments, the angle of incidence “Ai” with respect to the normal directions “N1”, “N2”, “N3”, “N4” and “N5” can be selected to optimize the intensity of the reflected beam reaching the detector202. At optimal angles of incidence the reflection from the normally-reflecting portions150of the oval gear200may produce beams of uniform intensity directed toward the detector202.

The normally-reflecting portion150can reflect beams of electromagnetic radiation to a detector202, thereby facilitating measurement of gear rotational count and/or speed. The normally-reflecting portion150does not span an entire circumference (e.g., 360 degree rotation) of the oval gear200. In the illustrated embodiment shown inFIG. 7A, the normally reflecting portion spans between about one-quarter to one-half of a circumference “D” of the oval gear200. The normally-reflecting portion150is therefore in the field of view of the detector intermittently as the oval gear200rotates. For example, the normally-reflecting portion150may be in the field of view of the detector once per full rotation of the oval gear200. The normally-reflecting portion150may remain in the field of view of the detector for an interval of time less than the time taken by the oval gear200to complete one full rotation. As a result, the beam reflected by the normally-reflecting portion150impinges on the detector intermittently during the rotation of the oval gear200. By counting the instances when the detector receives a signal due to reflection from the normally-reflecting portion150, the rotational count and/or speed of rotation of the oval gear200can be determined. For instance, the normally-reflecting portion150can be in the field of view of the detector for a fraction of a rotation interval. The rotation interval may correspond to the time taken by the oval gear200to complete one rotation (i.e., sweeping an angle of about 360 degrees to complete one rotation). In other words, when a beam of electromagnetic radiation is incident on the normally-reflecting portion150, the incident beam is reflected in a first direction “E”. In some embodiments, best illustrated inFIG. 7B, the first direction “E” makes an angle “Ar” with the normal direction “N”. In some embodiments, if the director is in-line with a beam emitter201(e.g., a single optical device serving as both emitter201and detector202), the first direction “E” is parallel to the normal direction “N”, and the reflected beam makes an angle of about 180 degrees with the incident beam direction “C”.

FIG. 7Cshows reflection from the non-normally reflecting portion152. The non-normally reflecting portion152has non-uniform orientations relative to incident beam and most of reflected beams do not reach detector202. The non-normally reflecting portion152reflects electromagnetic radiation into directions away from the detector202, (e.g., away from the detector202). As illustrated inFIG. 7A, the non-normally reflecting portion152reflects electromagnetic radiation in a second direction “F”. In certain embodiments, the second direction “F” makes an angle not equal to about 180 degrees with the direction of the incident beam “C”. The second direction “F” can make any angle other than 180 degrees with the direction of the incident beam “C”. If a detector is positioned in-line with the normal direction “N”, the detector may detect beams reflected by the normally-reflecting portion150, whereas beams reflected by the non-normally reflecting portion152may not impinge on or otherwise be sensed by the detector.

When the normally-reflecting portion150is in the field of view of the detector (e.g., phototransistor, camera etc.), it registers a reflected signal. For instance, a surface of the detector can be parallel to the plane of the normally-reflecting portion150. The surface of the detector can intercept the electromagnetic radiation reflected by normally-reflecting portion150. In contrast, if the non-normally reflecting portion152is in the field of view of the detector, it reflects electromagnetic radiation into directions other than those in line with the detector, and the detector may not register a signal. Based on the differences in the signal registered by the detector when the normally-reflecting portion150is in view, and the signal registered by the detector when the normally-reflecting portion150is not in view, the rotational count and/or rotation speed can be determined.

In some embodiments, the normally-reflecting portion150is made from the same material as the oval gear200. The normally-reflecting portion150, while illustrated as having a bean-shape, can have any shape and positioned anywhere on the surface of the oval gear. The normally-reflecting portion150can be substantially planar, and be level with the surface210of the oval gear200as seen inFIG. 7A. Alternatively, the normally-reflecting portion150may be higher than the surface210of the oval gear200by about 1/1000 inches (i.e., 1 mil) or about 1/500 inches (i.e., 2 mils). The normally-reflecting portion150can be manufactured by molding. The mold may result in a substantially reflective surface having a reflectance of between about 1% and about 30%. In certain embodiments, the substantially reflective surface has a reflectance of between about 5% and about 20%.

As seen inFIGS. 7A-9the non-normally reflecting portion152may include spiral, radial and concentric grooves154, or pins156as seen inFIGS. 11 and 12. As shown inFIG. 7A, the oval gear200includes a plurality of spiral grooves154to enhance detection of the beam reflected from the normally-reflecting portion150. In the illustrated embodiment shown inFIG. 10, the grooves154have a height “H”, and adjacent grooves154are spaced apart by a pitch “P”. As seen inFIG. 10, the grooves154may be formed such that they define a groove angle “A” between adjacent first and second sloping surfaces158,160. Electromagnetic radiation may be incident on the sloping surfaces of the grooves154(e.g., near peaks “X”, or valleys “Y”) and be reflected by an angle based on the groove angle “A”. For instance, a first beam of electromagnetic radiation can be incident on the first sloping surface158of the groove. The first beam of electromagnetic radiation can then be reflected by the first sloping surface158toward the second sloping surface160. The second sloping surface160may further reflect the first beam of electromagnetic radiation in a direction non-parallel (e.g., along second direction “F”) to the normal direction “N”. In the illustrated embodiments, the height “H” can be between about 0.1 millimeters and about 2 millimeters. The pitch “P” can be between about 0.3 millimeters and about 6 millimeters. The groove angle “A” can be between about 90 degrees and about 150 degrees. However, any height, pitch and groove angle can be used.

Without being bound by any specific definition, the dimensions, angle and pitch of the grooves154can be chosen so as to differentiate the signal detected by the detector due to reflection from the normally-reflecting portion150, by diverting reflected beams from the non-normally reflecting portion152away from the detector. Referring now toFIG. 10, in certain embodiments, the groove angle “A” can be any angle other than 90 degrees, to prevent an incident beam of electromagnetic radiation from being reflected by the grooves154(e.g., by multiple reflections on a first surface and a second surface of the groove) back to the detector. Additionally, the incidence direction “C” of the electromagnetic radiation can be chosen to avoid such back reflections from the grooves154to the detectors. For example, the grooves154may be designed such that groove angle “A” equals 30 degrees. Alternatively, the groove angle “A” can be 40 degrees. In alternate embodiments, the groove half angle A/2 can be any angle other than 45 degrees.

Referring back toFIG. 7Aand with reference toFIG. 10, the spiral grooves154may be contained within a ring162. The grooves154may be defined such that they cover122an entire circumference of the ring162. For instance, the spirals span 360 degrees about the axis “Z” of the oval gear200. Alternatively, the grooves154may be arranged symmetrically about the axis “Z” without having to cover122the entire circumference of the ring162. The grooves154can be made such that the ring162and peaks “X” of the grooves154can be higher than the surface of the oval gear200. For instance, the ring162and the peaks “X” can be between about 1/1000 inches (i.e., 1 mil) and about 1/500 (i.e., 2 mils) inches higher than the surface of the oval gear200. Adjacent peaks “X” can be of the same height as the ring162. Alternatively, the peaks “X” and the ring162can be of the same height as the surface of the oval gear200. The grooves154can be made such that the valleys “Y” of the grooves154can be below the height of the peaks “X”, the ring162and the surface of the oval gear200.

FIG. 11illustrates an oval gear200according to another embodiment. In the illustrated embodiment, instead of grooves154, the non-normally reflecting portion152of the oval gear includes a plurality of pins156extending therefrom. The pins156are conical in shape in the illustrated embodiment. However, the pins156can be of any shape such as cylindrical, hemispherical, pyramidal, or irregular shapes. Without wishing to be bound by any theory, any shape that prevents an incident beam of electromagnetic radiation from being reflected normally (e.g., reflected beam forming an angle of 180 degrees with respect to the incident beam) back to the detector can be used.

The pins156can be arranged in any manner. Any arrangement of the pins156that provides optimal reflection of electromagnetic radiation in a non-normal direction can be used. In the illustrated embodiment, the pins156are arranged in a randomly staggered arrangement in the central portion of the oval gear. In other examples, a periodic arrangement of pins156about the circumference can be provided. Alternatively, the pins156can be arranged such that they define concentric, radial or spiral curves. The pins156can be formed of the same material as the oval gear200. For instance, the pins156can be of PEEK. As is the case with the oval gear200surface, the pins156may also have a reflective finish and be of black or other dark colors. The pins156can be formed during the molding process used for forming the oval gear200.

While the illustrated embodiments shown inFIGS. 7A-11include grooves154and pins156, other non-normally reflecting portion152can include holes, dimples and the like as seen inFIG. 12. Although areas between the holes164that may absorb or otherwise “trap” the incident electromagnetic radiation (e.g., due to multiple internal reflections), such a non-normally reflecting portion152may still be used. Holes, dimples and the like may be machined from a molded portion of the oval gear200with a machining tool suitable for machining polymers such as PEEK. Embodiments such as those illustrated inFIGS. 7A-13can facilitate eliminating inserts, thereby resulting in an oval gear with fewer parts and lower costs than those with inserts. In the absence of inserts, measurement uncertainties due to improperly engaging the inserts on the gears can also be eliminated. In other embodiments, the normally-reflecting portion150may be polished as shown onFIG. 11andFIG. 12whereas areas surrounding the pins156or holes164have a grounded and/or unpolished surface finish. Electromagnetic radiation may be reflected by the polished areas (e.g., normally-reflecting portion150). Electromagnetic radiation will be scattered from grounded areas. Scattering may produce a difference in signals (e.g., sensed by detector202ofFIGS. 7B and 7C) from polished and grounded areas thereby allowing detection of gear rotation.

Embodiments of the oval gear meter disclosed herein can be useful for monitoring and measuring characteristics of flow in different systems. For instance, the oval gear meter can be used to detect chemical concentration, or to detect and measure flow volume, volumetric flow rate and other characteristics to prevent out of product conditions in a number of applications. Embodiments disclosed herein can lead to improved measurement accuracy. The simple design of the oval gear meter may result in low manufacturing costs.

Thus, embodiments of the invention are disclosed. Although the present invention has been described in considerable detail with reference to certain disclosed embodiments, the disclosed embodiments are presented for purposes of illustration and not limitation and other embodiments of the invention are possible. One skilled in the art will appreciate that various changes, adaptations, and modifications may be made without departing from the spirit of the invention.