Liquid level gauge with integral electronic display

An electronic liquid level gauge assembly includes an electronic display located in a housing connected to a tank. The display has first and second display portions for indicating liquid level condition. A first electronic sensor senses a change in magnetic field of a magnet associated with a liquid level transducer, with magnet rotation being proportional liquid level change. A processor determines a temperature-compensated liquid level condition by correlating the liquid level signal with temperature measurement of the liquid. A temperature-compensated vapor space can also be calculated based on tank information and properties of the liquid. Signals related to the temperature-compensated liquid level and vapor space are sent to the display and wirelessly transmitted to a smart phone or the like for remotely viewing the tank information. The smart phone also includes a special app for sending information, firmware updates, and display configuration data to the electronic gauge assembly.

BACKGROUND OF THE INVENTION

Delivery vehicles for pressurized fuel and other liquids, such as liquefied petroleum gas (LPG), propane, butane, and so on, typically include a large holding tank located rearwardly of the cab. A fuel sending unit is typically mounted at the center of the tank above eye level of the observer. The sending unit includes a float that rides on the surface of the liquid. The float is connected to a pivoting float arm which is in turn connected to the lower end of a driven shaft that rotates about its axis in response to float movement. A driving magnet is typically located at the upper end of the driven shaft that magnetically couples with a driven magnet inside the gauge head, which is associated with an indicator, so that rotational movement of the driving magnet in response to float movement induces the driven magnet to rotate a proportional amount and rotate the indicator across a scale associated with the gauge head, to thereby display a liquid level condition of the tank to an observer.

When such fuel gauges are mounted to large storage tanks associated with transportation vehicles, such as propane delivery trucks, the gauge head is typically mounted at the rear center of the tank to minimize errors in reading. However, such a location is usually above the operator's field of view, which makes it hard to accurately read the gauge due to parallax errors that occur when the eyes of an observer are not properly aligned with the indicator and scale.

In addition, such gauges also inconvenience an operator since the liquid level within the tank is not readily apparent unless the vehicle is parked on a level surface and the operator exits the cab and walks to the rear of the vehicle to observe the gauge reading. Even when the gauge reading can be manually observed, it may not be accurate within acceptable limits unless compensation of liquid level or volume is manually calculated based on the specific gravity of the particular liquid within the tank, which can be affected by temperature. Accordingly, an operator must have knowledge of the contents of the tank, its specific gravity at a set temperature, and expansion or contraction of the volume based on changes in specific gravity for a particular fluid at different temperatures. Consequently, obtaining a clear and accurate reading of the volume or level of liquid within such storage tanks can be both a difficult and time-consuming task.

It would therefore be desirous to provide a simple, straight forward solution that would reduce or eliminate parallax reading errors while avoiding high development and manufacturing costs associated with redesigning the gauge head, fuel sending unit and/or tank.

SUMMARY OF THE INVENTION

In accordance with one aspect of the invention, an electronic gauge assembly for indicating liquid level within a tank, the gauge assembly being operatively connectable to a liquid level sensor probe, and comprising a mounting base adapted for connection to the tank, a housing connected to the mounting base, an electronic display located in the housing and having a first display portion for displaying a liquid level condition within the tank, and a first electronic sensor connected to the housing. The first electronic sensor is couplable to the liquid level sensor probe such that a change in the liquid level sensor probe due to a change in liquid level causes a change in electronic state of the first electronic sensor. A processor is in communication with the first electronic sensor and includes means for determining a first liquid level condition within the tank based on the change in state.

In accordance with another aspect of the invention, a second electronic sensor for detecting a temperature of the liquid within the tank is also in communication with the processor. The processor includes means for calculating a second temperature-compensated liquid level condition based on the first liquid level condition and the temperature of the liquid, and sending signals representing the second liquid level condition to the first display portion for displaying the temperature-compensated liquid level condition.

In accordance with yet a further aspect of the invention, a method of measuring and displaying liquid within a tank includes providing an electronic gauge assembly having a processor in communication with a memory, an electronic display, a first sensor for sensing liquid level and a second sensor for sensing temperature of the liquid, determining a liquid level condition of the tank with the first sensor, determining a temperature of the liquid within the tank with the second sensor, calculating, with the processor, a temperature-corrected liquid level condition of the tank by correlating first information stored in the memory related to geometry of the tank and volume of liquid at any given liquid height, and correlating second information stored in the memory related to volume expansion and contraction for a range of temperatures, displaying at least one of temperature-corrected liquid level and temperature-corrected liquid volume on the electronic display, and communicating at least one of the temperature-corrected liquid level and volume wirelessly to a remote device.

Other aspects, objects and advantages of the invention will become apparent upon further study of the following description in conjunction with the attached drawings.

It is noted that the drawings are intended to depict only exemplary embodiments of the invention and therefore should not be considered as limiting the scope thereof. It is further noted that the drawings may not be to scale. The invention will now be described in greater detail with reference to the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, and toFIGS. 1 and 2in particular, a liquid level transducer10having an electronic gauge assembly12with an exemplary attached sensing probe assembly15(FIG. 9) in accordance with an exemplary embodiment of the invention is shown connected to a refueling vehicle14or the like. The vehicle14is only partially represented inFIG. 1and shows the rearward portion of a bobtail truck or trailer having a frame16supported on wheels18, a wheel guard or fender20extending along the frame and partially around the front and rear of the wheels, a rear bumper22connected to the frame14, mud flaps24extending downwardly from the bumper22, tail light assemblies26extending laterally from opposite sides of the frame16, and a holding tank28supported on the frame16. The tank28includes a generally cylindrical tank section30with a semispherical rear tank section32. A manway opening (not shown) is sealed by a manway cover34located on the rear tank section32above the transducer10for allowing manual access into the tank28. A shield38for protecting and shading the electronic gauge assembly12of the transducer10is mounted on the rear tank section32above the gauge assembly.

The tank28can contain, but is not limited to, liquid propane gas (LPG), methane gas, butane gas, natural gas, GLP, and other liquefied gases or combinations thereof, other cryogenic or non-cryogenic fluids, and so on. The vehicle12is intended to carry a large quantity of fuel or other liquid for refilling smaller tanks, such as permanently installed commercial or residential propane tanks, for delivering fuel to a home, vehicle, and other tanks or the like, as is well-known. The tank26may have a manway opening (not shown), which is typically formed in the rear portion30of the tank26, and a manway cover34that extends over and seals the opening32through a series of peripherally located fasteners36and one or more seals (not shown) to prevent loss of pressurized gas or liquid when in service. The tank26may include one or more manway openings and covers at other locations along the tank, such as when the tank is divided into several sections or segments, as is well known.

Referring toFIG. 1, a user40is illustrated standing next to the vehicle14and facing away from information displayed on the electronic gauge assembly12, yet able to receive and view such information on a display45associated with a smart device46, such as a smart phone, tablet, or the like, via wireless communications, such as radio frequency (RF) communications, as schematically represented by communication lines42,44inFIG. 1. The user40may be any person associated with the vehicle or tank, such as an operator, inspector, refueling technician, and so on. The readily available information can be viewed anywhere the RF carrier signal can be broadcast, including inside the cab (not shown) of the vehicle12, or within a broadcast range of the RF transceiver50(FIG. 12) of the electronic gauge assembly12. Accordingly, the user40need not walk to the back (or side) of a tank to retrieve vital tank information but is capable of receiving that information anywhere a wireless carrier signal can be transmitted and received by the user's device46, as will be described in further detail below.

With particular reference toFIGS. 2-5, the electronic gauge assembly12preferably includes a rear housing portion52, a sensor assembly54connected to the rear housing portion52, an electronic assembly56(FIG. 2) including a printed circuit board (PCB)58with various electronic components (not shown) connected thereto, as will be described in greater detail below, a display assembly59includes a first display portion60connected to the PCB, a second display portion62located above the first display portion60and also connected to the PCB58, a transparent protective lens64to protect the display portions, and a front housing portion or bezel66connected to the lens64and the rear housing portion52for enclosing the above-described components. An electrical receptacle68is attached to the rear housing portion52and includes a plurality of pins70(FIG. 4) associated with the electronic assembly56for connection with a wiring harness (not shown) associated with the vehicle, tank, system, or machine associated with the tank. The wiring harness (not shown) is connected to a power supply72(FIG. 6), such as the power supply of a vehicle, external battery, line power, and so on, for example, for providing electrical power to the electronic assembly56and displays60and62. The electronic assembly56is also capable of transmitting, via the receptacle68and wiring harness, signals to an external display (not shown) indicative of conditions inside the tank28(FIG. 1) including temperature, pressure, liquid type, specific gravity, density, liquid level, vapor space, and so on, ambient conditions outside of the tank such as temperature, humidity, atmospheric pressure, vehicle tilt, and so on, as well as other conditions and/or measurements. The external display may be associated with the vehicle, a portable display associated with a tablet46(FIG. 1) or other smart device, and so on.

The rear housing52includes a rear wall74with a depression76having first generally circular depression portion78for receiving the sensor assembly54, and a second generally elongate depression portion80for accommodating the shape of the receptacle68. A continuous side wall82extends forwardly from the rear wall74and includes a lower opening84that receives the side wall86of the receptacle68. A bottom wall88of the receptacle rests against the side wall82of the rear housing52and is connected thereto through mechanical fastening, adhesive bonding, ultrasonic welding or any other connection means so that the receptacle68stays in place when connecting or connected to a wiring harness (not shown) of the vehicle or system associated with the tank28. Spaced mounting bosses90and92extend forwardly from the rear wall74of the rear housing52and include openings94. Corresponding openings95(FIG. 2) are also formed in the front bezel66and openings101are formed in the lens64. Threaded fasteners97extend through the openings95of the front bezel66, openings101of the lens64, and the openings94of the bosses90,92of the rear housing52for securing together the electronic gauge assembly12. Mounting apertures96are also formed in the rear wall74that align with corresponding mounting apertures98formed in the PCB58and mounting apertures100formed in the first display portion60for mounting the first display portion60to the PCB58and the rear housing52via threaded fasteners99(only two shown for clarity inFIG. 2), standoffs, or the like that extend through the apertures100,98and96, respectively.

The PCB58includes side depressions102and104for receiving the mounting bosses90,92respectively. Various electronic components of the electronic assembly56are connected to a rear side106of the PCB58, while the first display portion60and second display portion62are connected to a front side108of the PCB58for viewing by an observer through the transparent protective lens64.

As best shown inFIG. 5, the generally circular depression portion78formed in the rear wall74of the rear housing52has retainers110,112, and114for holding a sensor PCB116of the sensor assembly54. The sensor assembly54also includes a sensor118or the like, preferably in the form of a magnetic field sensor, for detecting rotational movement of an actuator120, preferably comprising a magnet, through the rear wall74of the rear housing52. The magnet120is connected to an upper end of a shaft122for rotation therewith about a first rotational axis121of the shaft122, as represented by arrows124, upon a change in liquid level inside the tank, as will be described in greater detail below.

The actuator magnet120can have an anomaly126, shown as a slot for example, so that the magnetic field is non-uniform. Other anomalies can include thicker and thinner magnetic sections, sloped magnetic surfaces, rectangular-shaped magnets, magnets having different polarity signatures, one or more magnets that are offset from the first rotational axis121and so on. It will be understood that the anomaly may be removed when certain types of magnetic sensors are used.

By way of example, magnetic sensors can include, but are not limited to, one or more solid state magnetic flux field sensors, Hall effect sensors, magnetoresistive (MR) sensors, anisotropic MR (AMR) sensors, giant magnetoresistance (GMR) sensors, solid state Micro-Electro-Mechanical Systems (MEMS), magnetic switches, as well as nonmagnetic sensing technologies such as proximity detectors using capacitance, optical, or other measurement technologies, and so on. With the use of the above sensors, it may not be necessary to have the sensor in alignment with the central axis of rotation of the magnet, or a plurality of sensors, since a single Hall effect IC may be sufficient to determine the position of the magnet and thus the level of liquid within the container.

It will be appreciated that the invention is not limited to actuators and sensors for generating and sensing magnetic fields or changes in magnetic fields during rotation of the actuator120, but may include other types of actuators and sensors for determining liquid level or other tank conditions. For example, the sensor118can be in the form of one or more optical sensors for use with optical actuators, such as LED's or other light source, as well as other contactless actuator/sensor arrangements to remotely change the electrical state of the sensor to thereby generate a liquid level signal in response to rotational movement of the shaft122. In the event that optical actuators/sensors are used, the housing can be formed of a material that is translucent or transparent to the wavelength of the light source so that the sensor can readily detect movement of the light source as the liquid level in the container rises and falls.

Referring toFIGS. 2 and 3, the first display portion60preferably comprises electronic display technology such as LCD, LED, or OLED panels, as is well-known, or new technology that may become available. The display portion60is divided into display sections for indicating various conditions of the tank28(FIG. 1), including a first exemplary display section130that shows the level and/or volume of the tank as a temperature-compensated percentage where 0% is an empty tank condition and 100% is a full tank condition. The first section130can additionally and/or alternatively display remaining gallons (or liters) of liquid within the tank, the volume of a gaseous phase of the liquid or the vapor content of the tank above the liquid, which is important for pressurized fuels in both liquid and gaseous states such as propane, natural gas, and so on, as well as other information relating to the contents of the tank and/or conditions within the tank. The display of different information may be controlled in the first section130by scroll buttons (not shown), the provision of a touch-sensitive display for the first display portion60where swiping actions by the user will scroll to different images representing the tank information, as well as control of the display portion60remotely via a smart device, as well as other techniques, hardware, and software methods for sequentially displaying different information.

The first display portion60also includes a second exemplary display section132that shows the specific gravity of the liquid within the tank, as well as other information including ambient temperature, tank temperature, tank pressure, and so on, again through sequential scrolling techniques as discussed above. A third exemplary display section134shows the internal tank temperature in Fahrenheit, and alternatively in Celsius, and can additionally or alternatively display the temperature of the gaseous phase and/or liquid phase within the tank, the outside ambient temperature, tank pressure, outside ambient pressure, and so on. A fourth exemplary display section135shows tank temperature displayed in Celsius, but may also or alternatively display other information as discussed above. A firth exemplary display section136and sixth exemplary display section138preferably include a first alarm indicator140and a second alarm indicator142, respectively, which may comprise one or more LED's that illuminate or flash when certain conditions have or are occurring that may be of concern to a user. For example, excessively high or low levels of liquid in the tank, tank pressure that drops below a low threshold or exceeds a high threshold, and so on. Such alarm sections can also be used for indicating that fill or distribution valves are not fully closed or open, or that the vehicle is improperly parked (with the vehicle in neutral or without the emergency brake set for example), as well as other conditions that might be of concern to a user. Such conditions can be more fully displayed in the first and/or second display sections.

A seventh display section144can be used for permanently or temporarily displaying a company name, advertisements, instructions and warnings, and so on. The seventh display section can be made by placing or adhering a printed adhesive label on the transparent lens64(FIG. 2) or other substrate, and/or by silk-screening such information onto the lens or other substrate. To that end, additional LED's146can be provided behind the lens64within the seventh display section144for back-lighting the printed matter of the seventh display section142.

It will be understood that more or less display sections can be used and that more or less information can be displayed without departing from the spirit and scope of the invention.

The second display portion62preferably comprises a series of bargraph display sections150,152,154, and156for example, each bargraph having ten LED segments158. Each LED segment represents a predetermined percent of temperature-compensated volume of liquid in the tank. A scale160extends along the length of the bargraph display sections for indicating the percent volume by observing the number of LED segments158that are illuminated next to the scale160. As shown inFIG. 3, the cross-hatching of the LED segments up to about 90% represent a green color, meaning that the contents of the tank are at an acceptable volume or level. Likewise, the cross-hatching of the LED segments around 90% and above represent a red LED color, indicating that the contents of the tank are approaching or above an unacceptable volume or level. Since liquid expands with increase in temperature, it is standard practice to fill the tank up to a particular level below completely full to allow for expansion of liquid. The second display portion62of the invention, together with the alarm sections of the first display portion60, ensure that a user is aware of the tank28(FIG. 1) being too full, so appropriate action can be taken.

It will be understood that the LED segments can be provided on the PCB56(FIG. 2) as a series of individual LED's rather than the bargraph displays. It will be further understood that the colors of the LED segments are not limited to green and red, but can emit light at any color without departing from the spirit and scope of the invention.

With reference now toFIGS. 6 and 7, the electronics assembly56for determining various tank and ambient conditions and for driving the display portions60and62preferably includes a processor a processor174, the sensor118for detecting liquid level (labeled “Sensor1”).

A temperature sensor176(labeled “Sensor2”), such as a thermocouple, thermistor, or silicon bandgap temperature sensor, located in a pocket (not shown) in the tank normally reserved for a mechanical temperature sensor, for measuring the temperature of the liquid inside the tank. The temperature sensor can be used with a look-up table stored in memory to adjust the actual volume of liquid based on the type of liquid in the tank and the temperature of the liquid. For example, propane, iso-Butane, n-Butane, and NH3 will have different temperature compensation factors for the same temperature, with the exception of 60 degrees Fahrenheit, where the actual volume or level of fluid in the tank is at unity for each liquid type as a base reference. Below 60 degrees, each liquid will have a correction factor above unity, which generally increases as the liquid expands under lowering temperatures. Above 60 degrees, each liquid will have a correction factor below unity, which generally decreases as the temperature rises. Accordingly, when displaying temperature-compensated liquid level, a simple math operation is performed with the processor based on the detected temperature and the measured liquid level to obtain actual liquid level.

In accordance with one embodiment of the invention, since many storage tanks are strapped, strapping information for the particular tank associated with the electronic gauge assembly12can be uploaded as a strapping table into permanent memory and used to determine tank contents in gallons, liters, and/or other units of volume. Since there are a variety of tank sizes and shapes, strapping information for different tanks would also be different. When the actual volume in gallons or liters is displayed, strapping information relating to tank geometry and the volume of liquid at a particular height with respect to the geometry is also stored in a look-up table for access by the processor. Accordingly, when the processor determines temperature compensated liquid height, the strapping lookup table is accessed by the processor to correlate the temperature-compensated height to with actual volume at that height, thereby obtaining temperature-compensated volume in gallons, liters, or other units of volume. Accordingly, the present invention can display temperature-compensated volume of the liquid within the tank.

A pressure sensor178(labeled “Sensor3”) can be provided for measuring the internal pressure of the tank. Other sensors can be provided as well, including sensor180(shown in dashed line and labeled “Sensor n”) located inside and outside of the tank28(FIG. 1) for determining various conditions, such as ambient temperature and pressure outside of the tank, whether or not filling and/or distribution valves are fully closed, and so on. The designation “Sensor n” refers to any number of sensors that can be used to measure different conditions of the tank, the vehicle or system associated with the tank, as well as ambient conditions outside of the tank.

Amplifier and offset control circuitry182interfaces between the processor174and sensors118,176,178,180, and so on, for conditioning the signals from the sensors prior to being received and processed within the processor. It will be understood that the amplifier and offset control circuitry182may alternatively form part of the processor software or may be eliminated without departing from the spirit and scope of the invention.

A radio frequency (RF) transceiver50is also connected to the processor74for sending signals to the display45(FIG. 1) of the smart device or remote display unit46for displaying various measurement data from the sensors118,176,178,180, as well as other sensors, as will be described. The RF transceiver50can also receive signals from the remote smart device46for initiating various functions such as remotely turning on and off the display portions60and62, verifying the receipt of transmitted information, loading software updates to the electronic gauge assembly12, and so on.

In accordance with a preferred embodiment of the invention, the RF transceiver comprises a Bluetooth low energy (BLE) module for communicating with smart devices via the same protocol, which may in turn be connected to the Internet via Wi-Fi, so that one or multiple electronic gauge assemblies can be monitored, updated, calibrated, and effect the electronic transfer of tank information remotely via the Internet on any device with a compatible platform. In accordance with a further embodiment of the invention, the RF transceiver comprises a Wi-Fi device capable of directly communicating with the Internet for remotely accomplishing the above-described functions. In this embodiment, the RF transceiver broadcasts over Wi-Fi frequencies and also has a dedicated modem or other device for accessing 3G, 4G or other cellular networks for access to the Internet when such services are not readily available. It is contemplated that other RF transceivers can be used with a variety of different carrier frequencies, such as radio bands with 433.92 MHz, 915 MHz, and 2400 MHz frequencies, short range devices at 315 MHz and 868 MHz frequencies, as well as defined protocol communications via ZigBee™, Bluetooth low energy (BLE), and Wi-Fi, at 2.4 Ghz, 3.6 Ghz, and/or 5 Ghz, or any other suitable protocol.

The RF transceiver50is preferably located at a position on the PCB56(FIG. 2) that minimizes RF interference and maximizes the distance or range over which the signals can be transmitted. A user input, such as one or more push-button switches184(FIG. 6), can be mounted on the PCB56for manipulation by a user to selectively turn on and off the displays, scroll through different information on the displays, as well as other functions, including but not limited to, entering a learn mode to couple the electronic gauge assembly12with a particular smart device46(FIG. 1), entering a calibration routine or other functions relating to the contents of the tank, and so on. The transceiver50can also receive signals from the remote smart device46for initiating various functions, as previously described. By way of example, the low energy Bluetooth connection between the smart device and the electronic gauge assembly includes a platform-specific application (app) on the smart device for configuring the electronic gauge assembly including the display portions60and62. Thus, the user is able to input key setup parameters for the gauge including, but not limited to: entering the specific gravity of the liquid in the tank, selection of preferred temperature units: ° C. or ° F., Alarm1on/off selection, Alarm2on/off selection, Alarm1trigger percentage, Alarm1trigger slope (increasing level or decreasing level), Alarm1delay, e.g. a predetermined time period, such as 30 seconds for example only, that the alarm condition has been met prior to activating the alarm, Alarm2trigger percentage, Alarm2trigger slope (increasing level or decreasing level), Alarm2delay (similar to Alarm1delay, the tank geometry specific data, tank Level—both uncompensated and temperature compensated level should be provided via the BLE link, tank temperature should be provided via BLE link in the desired units, turning on and off advertising information on the display. This feature is to allow advertisements to be displayed on the bobtail while traveling for example, so that other drivers may be exposed to advertising, which may be an additional source of revenue for companies and individuals using the electronic gauge assembly.

A GPS unit186can also be provided to determine instantaneous velocity as well as the location of the vehicle at all times. This information can be relayed to the remote smart device46and/or a remote location for monitoring by a control station or the like for determining the location of a fleet of bobtails or the like. The GPS unit can also be useful for alerting a driver when, based upon the calculated remaining gallons of liquid, whether the driver can continue with a refilling route or return to the base station for filling the storage tank.

A three-axis accelerometer188can also be provided to determine acceleration, deceleration, instantaneous velocity, centrifugal forces experienced while turning through curved sections of a roadway, and so on. Data from the accelerometer can be used to determine actual liquid level despite changes in the upper surface of the liquid due to acceleration forces to ensure that a steady level or volume of fluid is displayed.

A three-axis tilt sensor190is preferably provided for determining whether the vehicle, and thus the tank, is on a sloped surface, both lengthwise and width-wise, which would effectively change the plane of the liquid upper surface with respect to a sensor that uses the upper surface to determine liquid level or volume. With the angle of the slope being known, as well as the geometry of the tank, the processor174can be used to calculate actual level so that errors in displaying incorrect liquid level or volume are minimized.

A three-axis gyroscope192can also be provided to the upper surface of the liquid with respect to the tank, as the upper surface will always be perpendicular to a gravitational force vector, while the vehicle and tank may not. Accordingly, the gyroscope192is useful for ensuring that actual tank volume or level is displayed. Although the accelerometer, tilt sensor and gyroscope are shown as separate units inFIG. 6, it will be understood that a 9-axis accelerometer/gyroscope/tilt sensor can be used. Such devices are widely available at relatively low cost and can be interfaced with the processor174for calibrating the liquid level and/or volume of liquid in the tank with practically any scenario to ensure accurate display of the tank condition, whether the tank and its contents are stationary or moving, whether on flat or sloped surfaces, and so on. The data gathered from the various sensors can be stored in a memory194associated with the processor174and a data output interface196can be provided in order to store, process and display the recorded data on a display, such as display portions60and62(shown in broken line), as previously described.

The real-time compensation process associated with ensuring accurate liquid level and/or liquid volume within the tank can be gathered and processed through known data processing techniques using computer algorithms or software for various platforms and can be provided as computer readable software on various media storage devices for downloading into and operating on a smartphone, a computer, display, or the like, including but not limited to, hard drives, Internet websites, thumb drives, flash memory devices, CD's, and so on.

In accordance with a further feature of the invention, with the above-described electronics and software implementation both embedded in the electronic gauge assembly12and the user-specific app on the smart device, the calculation of vapor content within the tank28is possible. To do so, the processor accesses the strapping information of the particular tank of interest where tank geometry is correlated to liquid height and volume, as well as tank pressure information from the pressure sensor178(FIG. 6), the volume of the vapor space above the liquid can be calculated. This is especially advantageous for liquids such as propane.

By way of example, if it is known that the tank28has a 10,000-gallon water capacity, and the temperature-compensated level reading is calculated at 75% full, and the tank pressure is 100 psig, the processor174(FIG. 6) accesses a vapor space lookup table where gauge pressure is correlated to gallons (or other volume units) for the vapor space. A simple mathematical operation is performed by the processor by multiplying the gallons or other unit located on the lookup table by the water capacity of the tank. For the present example, for 100 psig tank pressure, the value in the lookup table is 0.0287 gallon. The mathematical function would therefore be multiplying gallons from the lookup table by the water capacity, e.g. 0.0287×10,000=287. Since the vapor space is equal to 25% of the total volume (since the temperature-compensated liquid level was calculated at 75% in the example above), the processor multiplies gallons by the vapor space, for example, 287 gallons×25%=72 gallons of vapor space. The following vapor lookup table for propane is given by way of example only, and is based on typical value of 36.39 cubic feet of gas to one gallon of LPG:

In accordance with a further embodiment of the invention, a separate pressure sensor may not be needed as the processor can calculate the tank pressure with the following lookup table correlating propane temperature with pressure:

Having a more complete picture of the amount of propane in the tank (in both liquid and vapor phases) is advantageous to the user, as the vapor phase of propane and similar fuels is most often used to run propane-powered vehicles and equipment.

It will be understood that the various measured and calculated parameters as described above are given by way of example only and are not intended to be an exhaustive list. Software techniques and methods for accurately determining the liquid level, volume and other tank conditions as discussed above can be implemented in digital electronic circuitry, or in computer hardware, firmware, software, or combinations thereof. Apparatus may be implemented in a computer program product tangibly embodied in a machine-readable storage device for execution by a programmable processor; and the above-described methods may be performed by a programmable processor executing a program of instructions to perform functions by operating on input data and generating output. Further embodiments may advantageously be implemented in one or more computer programs that are executable on a programmable system including at least one programmable processor coupled to receive data and instructions from and transmit data and instructions to a data storage system, at least one input device, and at least one output device. Each computer program may be implemented in a high level procedural or object-oriented programming language, or in assembly or machine language, which can be compiled or interpreted. Suitable processors include, by way of example, both general and special purpose microprocessors. Generally, a processor receives instructions and data from read-only memory and or RAM. Storage devices suitable for tangibly embodying computer program instructions and data include all forms of non-volatile memory, including by way of example semiconductor memory devices, such as EPROM, EEPROM, and flash memory devices; magnetic disks such as internal hard disks and removable disks; magneto-optical disks; and so on. Any of the foregoing may be supplemented by, or incorporated in, specially designed application specific integrated circuits (ASIC's).

Referring toFIGS. 7 and 8, the remote smart device46is preferably embodied as a smartphone or tablet that can communicate via Bluetooth™ technology and/or other wireless frequencies with the electronic gauge assembly12via a user-specific application (app) downloaded onto the smart device. The smart device46includes a housing200(FIG. 8) that encloses an electronics section202(FIG. 7). A window204is formed in the housing200for exposing the touch-screen display45, that is in turn connected to a processor206. A RF transceiver208, such as a BLE for example, is preferably connected to the processor206for receiving measurement signals from the electronic gauge assembly12and transmitting information related to tank geometry including strapping information and look-up tables as previously described, information for the particular liquid to be measured in the tank, program updates and instructions to the gauge assembly as previously described. A power supply210is connected to the processor206and transceiver208. The power supply comprises one or more batteries so that the smart device46has portability. A user input, such as push-button switch212A,212B, extend from the housing200for manipulation by a user, together with the touch-screen45, to selectively turn on and off the display45and/or59of the gauge assembly12, as well as to select other functions, including but not limited to, wirelessly coupling with the electronic gauge assembly12, selecting information to be displayed on both devices, selecting information to be transmitted to the electronic gauge assembly related to tank geometry, liquid properties, look-up tables, and so on, for use by the processor174.

The provision of a remote display that can be carried by a user, as shown inFIG. 1, is especially advantageous over prior art solutions that require the user to be at the rear or side of the tank to determine the amount of liquid within the tank. This is especially true of bobtails or other tanker trucks where the only liquid level gauge is located at the rear of the tank. Such prior art gauges are mechanical in nature and have many disadvantages when compared to the present invention, since communication of tank information to a more convenient and possibly safe location is enabled, along with liquid level or volume information that is both temperature compensated and calibrated for tilt and acceleration/deceleration forces. Such a provision also allows a user to constantly monitor tank contents and other parameters during transportation along roads that have steep upward or downward grades, curves, and other instances where acceleration and/or gravitational forces may have an incorrect influence on the measurement of liquid level and/or liquid volume within the tank. Moreover, such a provision also allows information wirelessly transmitted to the electronic gauge assembly to be completely controlled by the smart device. This allows the end user to customize the gauge assembly and accompanying display for a specific tank, liquid to be measured, and type of sensing probe used to measure the liquid level.

As shown inFIG. 8for example, some of the information with can be displayed on the smart device46(and also transmitted to the electronic display60) is a graphical image of liquid level214, a “Liquid Level (Temp. Compensated) label216followed by a numeric display of the percent liquid level or volume218. A label and numerical value for the number of gallons (or liters) remaining in the tank are displayed at220and222. Likewise, a label and value for vapor volume remaining in the tank, as calculated, are displayed at224and226. At228and230, a label and actual value for the temperature of the liquid in the tank are displayed. AT232and234, a label and numeric value for the total amount of liquid dispensed from the vehicle during the day, are displayed. At236, a gross profit for the day's deliveries is displayed. Of course, it will be understood that the above information is given by way of example only and the actual information can vary depending on the particular requirements of a particular tank, the properties of a particular liquid or liquids to be measured, and the particular level sensing probe being used.

Referring now toFIGS. 9-13, the sensing probe assembly15is shown connected to the electronic gauge assembly12. Although a particular sensing probe and its mounting arrangement with the electronic gauge assembly12will be shown and described, it will be understood that the electronic gauge assembly of the present invention can be used with any float-type liquid level transducer or any solid-state liquid level transducer where liquid level signals can be transmitted to the electronic gauge assembly12in practically any application and/or location where indication of liquid level is desirous. Accordingly, it is anticipated that the electronic gauge assembly12can be used with capacitance-type liquid level probes, reed switch-type probes, and so on.

The sensing probe assembly15includes a gauge head240with a mounting base242adapted for mounting on the wall243(FIG. 13) of the tank28(FIG. 1). The electronic gauge assembly12is connected to the mounting base242via a pair of brackets244and246that are located between the mounting base242and the rear wall74of the rear housing52of the electronic gauge assembly12. The mounting base242is shown as generally circular in shape and includes apertures248that align with apertures250formed in the tank wall243. Fasteners (not shown) extend through the apertures for connecting the mounting base242to the wall. Instead of apertures in the tank wall, threaded studs may extend through the tall for engaging the apertures248of the mounting base242in a known manner for connecting the components together.

The sensing probe assembly15also includes a tubular support member320that extends downwardly from the gauge head240and houses the driven shaft122(FIGS. 5, 12 and 13) that in turn rotates a magnet120(FIG. 5) or other actuator for detection by a magnetic field sensor118or the like, as previously described. The tubular support member320and driven shaft122can be provided in different lengths to accommodate a wide variety of different tank depths.

A gear assembly324is located at a lower end of the tubular member320and includes a driving gear326rotatably connected to an inner yoke330(FIG. 10) and a driven gear328connected to the driven shaft122for rotation therewith. The driving gear326and driven gear328are coupled together such that rotational movement of the driving gear results in proportional rotational movement of the driven gear328and thus rotation of the shaft122to ultimately drive the display portions60and62(FIG. 3). The inner yoke330is connected to the lower end of the tubular member320. The driving gear326is rotatably connected to the inner yoke330via a pivot pin332(FIG. 12) that extends through the driving gear326and inner yoke330. The driving gear326is preferably fixedly connected to the pivot pin which is in turn rotatably connected to the inner yoke330about a pivot axis334(FIG. 9).

An outer yoke336includes a pair of arms338,340that are fixedly connected to the pivot pin332for rotation therewith about the pivot axis334. A cross member342extends between the arms338,340and includes a threaded opening344(FIG. 10) for receiving the threaded end of an insert346. A float rod348has a proximal end349that is received over the insert and secured thereto with a bolt350that extends through the float rod348and insert346. A nut352is received on the end of the bolt350to thereby securely connect the float rod348to the outer yoke336. The float rod348can be provided in different lengths to accommodate a wide variety of different tank sizes and configurations.

A float354is connected to a distal end356of the float rod348via an insert358that is connected to the float and received in the distal end356of the float rod. A bolt360extends through the float rod348and insert358and a nut362is received on the end of the bolt360to thereby securely connect the float354to the float rod348. The float354can be provided in different lengths, widths, shapes, configurations, materials, densities, can be solid or hollow, and so on, to accommodate a wide variety of different liquids to be measured.

A U-shaped bracket364fits within the outer yoke336and is biased toward the gear assembly324by a compression spring366located between the cross member342and the bracket364. A spring guide368is connected to the bracket364and extends into the spring366. Stop members370are preferably mounted on the arms338,340to limit bracket travel toward the gear assembly.

A counterweight assembly372is preferably connected to a distal end374of the outer yoke336. The counterweight assembly372includes a first weight portion378connected to the yoke arm338and a second weight portion380connected to the yoke arm340via fasteners382, such as rivets. However, it will be understood that one or both weight portions can be connected to the arms338,340via threaded fasteners, clamps, welding, adhesive bonding, and other connection means, as well as being integrally formed or machined with the yoke arms, without departing from the spirit and scope of the invention. It will be further understood that a single weight portion can be used or both weight portions can be eliminated when the arms338,340are sufficiently heavy to counteract the forces applied by the float and float rod. In addition, it will be understood that one of the yoke arms can be eliminated if a single yoke arm and/or weight are sufficient to counteract the float and float rod forces.

Although a particular embodiment for the sensing probe assembly15has been shown and described, it will be understood that other mounting arrangements as well as other sensing probe configurations can be used without departing from the spirit and scope of the invention. For example, a one-inch NPT threaded mounting opening is common on many types of holding tanks and therefore it is within the purview of the present invention to provide appropriate mounting heads for any tank mounting configuration for connecting the electronic gauge assembly and the sensing probe assembly to the tank wall.

Moreover, it will be understood that other sensing probes can be used in conjunction with the electronic gauge assembly of the invention, including but not limited to spiral rods that rotate upon linear float movement, float rods that rotate with the driven shaft as set forth for example in U.S. application Ser. No. 15/490,881 to Herbert G. Ross, Jr. filed on Apr. 18, 2017, the disclosure of which is hereby incorporated by reference, as well as stationary sensing probes that use reed switches, capacitance, resistance, time domain reflectometry, heated wire or plate technology, and so on, without departing from the spirit and scope of the invention. Another suitable exemplary liquid level sensing probe is disclosed in U.S. Pat. No. 5,357,815 assigned to Rochester Gauges, Inc., the disclosure of which is hereby incorporated by reference. Details of another suitable sensing probe can be found in U.S. Pat. No. 6,041,650 assigned to Rochester Gauges, Inc., the disclosure of which is hereby incorporated by reference. Accordingly, it will be understood that other sensing probes can be used with the electronic gauge assembly of the present invention without departing from the spirit and scope thereof.

It will be understood that the term “preferably” as used throughout the specification refers to one or more exemplary embodiments of the invention and therefore is not to be interpreted in any limiting sense.

It will be further understood that the term “connect” and its derivatives refers to two or more parts capable of being attached together either directly or indirectly through one or more intermediate members. In addition, terms of orientation and/or position as may be used throughout the specification denote relative, rather than absolute orientations and/or positions.