GB2614762A - Fano based crab sensor and system for fuel quality, level, and volume monitoring for irregular shaped fuel tanks - Google Patents

Abstract

A fuel monitoring system 100 includes an ultrasonic sensor 106, a Fano-based crab sensor 112 and a control module 102, 104 coupled to the sensors. The ultrasonic sensor is mounted to a fuel tank to measure or detect a fuel level of fuel in the fuel tank. The Fano-based crab sensor is mounted inside the fuel tank to monitor a quality of the fuel in the fuel tank. The Fano-based crab sensor may comprise a microstrip structure printed on a support structure 110, and may have a plurality of sensing elements at different heights. The fuel monitoring system may include a proximity sensor 108 to measure or estimate a size of the fuel tank, a flow monitoring device 116 at an input to the fuel tank and/or a cap sensing device 118 to sense a state of a lid of the fuel tank.

Description

FANO BASED CRAB SENSOR AND SYSTEM FOR FUEL QUALITY, LEVEL, AND VOLUME MONITORING FOR IRREGULAR SHAPED FUEL TANKS

FIELD OF THE INVENTION

[0001] This invention relates to a fuel level monitoring sensor and related devices and systems for use in but not limited to automobile fuel tanks and larger fuel storage tanks. Aspects of the invention further relate to monitoring the quality of fuel inside the fuel tanks.

Aspects of the invention further relate to fuel flow sensing in the fuel tanks. The disclosed invention can work for regular and irregular-shaped fuel tanks, as evident from the embodiments and accompanying drawings.

BACKGROUND (PRIOR ART)

[0002] Monitoring the fuel quality and level inside the automobile fuel tanks and large fuel storage tanks has been a topic of research for decades. Usually, the automobile contains the level sensor, which indicates only the fuel level inside the tank. The fuel quality sensor may also be important for good performance and engine life. Traditional fuel level monitoring sensors cannot detect the fuel level if an equal amount of any other liquid (or water) has been added to it. The problem becomes more complicated when the tank's shape is irregular. In this regard, the scientific community has put a lot of effort into making a sensor that can detect the quality and level of fuel at the same time. Techniques for level detection and quality monitoring are different and combining them in one device multiplies the problem's complexity.

[0003] One of the conventional ways of monitoring the level is using a floating sensor, and it changes its position according to the height of the liquid under test [Error! Reference source not found.]. These types of sensors are common and can convert mechanical energy into a detectable electrical signal. The sensor could be resistive or capacitive and measures the change in the resistance or capacitance, proportional to the change in the liquid level under test. Mostly the sensors are pre-programmed and calibrated according to one type of fuel tank.

[0004] The other type of sensor is the ultrasonic level monitoring sensor. These sensors work under the doppler effect and give a good indication of the liquid level under test [[2]-[4]]. These sensors are widely available in the market, but they are costly compared to electromechanical level monitoring sensors. An advantage of ultrasonic sensors over electromechanical sensors is the non-invasive sensing.

[0005] Optical sensors are more accurate and sensitive, but they are too expensive for domestic applications compared to ultrasonic and electromechanical sensors [[5]-[9]. A light beam strikes and reflects from a surface of the liquid under test, giving an indication about the fuel level inside the tank.

[0006] Another standard method of level sensing in fuel tanks is using capacitive sensors, which detect the change in the capacitance concerning the fuel sample under test. This type of sensor can also be used to detect the quality of the fuel as well [[10][15]]. These sensors are bulky and are not highly sensitive, which means they cannot be potentially used to detect the small impurities in pure samples. Electromagnetic (EM) fields between the plates of capacitors are not strong enough to detect a minimal change in the dielectric constant of the fuel. The low spatial resolution of the capacitance-based sensors results in less accurate readings or, in some cases, false-positive readings.

[0007] On the other hand, quality monitoring is more complex compared to level sensing. Different fuel properties like viscosity, density, and dielectric constant can be potentially used for quality monitoring. In addition, other properties (colour, flash point, thermal stability) need chemical testing. The effect of different types of contamination on fuel properties is given in Table 1 [[16]]. It can be seen from the table that all kinds of contaminations have a substantial effect on the dielectric constant of the fuel.

Table 1 Effect of different types of contamination on fuel properties Ref: J.C.

Schneider, MS Thesis, "Fuel Composition and Quality Sensing for Diesel Engines, UIUC, 2011) [0008] The fuel quality can be estimated electronically by measuring the change in capacitance, conductance, dielectric constant, viscosity, and density of the fuel under test. Spectroscopy is yet another technique used to detect fuel quality. Chuk et al. used different techniques like Fourier Transform Infrared (FT-IR) spectroscopy, refractive index, and UV-VIS spectroscopy to experimentally determine the fuel's blend levels for real-time sensing and monitoring. [[19]].

[0009] In US Pat. No. 5,194,910, Kirkpatrick et al. uses optical spectrometry to evaluate used motor oil conditions [[20]]. The proposed technique measures metallic wear debris contamination in used motor oil.

[0010] All the existing techniques based on spectroscopic methods use bulky and expensive equipment; techniques are complex and hence not suitable for low power, portable fuel sensing applications.

[0011] Due to the high penetration ability of subwavelength waves, microwaves sensors get attention in material sensing and characterization. An increasing number of non-invasive methods based on microwave material detection methods are available.

Density E.FttetcSitUatibtlw-Os ty nt Water contamination Small increase Small increase Large increase Urea contamination Small change Small change Large change Glycerol contamination Large increase Small increase Large change Methanol contamination No change No change Medium change Sulphur contamination No change No change Small Increase ru *Diel pc [0012] The Applicant desires a small but yet highly sensitive sensor.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Details of one or more implementations of the subject matter of the invention are outlined in the accompanying drawings briefly described below and the related description set forth herein. Other objects, features, aspects, and advantages will become apparent from the description, the drawings, and the claims. Note that the relative dimensions of the drawings may not be drawn to scale. Like reference numbers and designations in the various drawings indicate like elements.

[0014] FIG. 1 shows a complete fuel level and quality monitoring sensing system.

[0015] FIG. 2 shows the working of level sensing in an inclined plane.

[0016] FIG. 3 shows the user interface and display box.

[0017] FIG. 4 shows the knob to adjust the angle of the proximity sensor.

[0018] FIG. 5 shows the position of the ultrasonic, microwave crab, and proximity sensor.

[0019] FIG. 6 shows the lever position and position of the transmitter and receiver of the proximity sensor.

[0020] FIG. 7 shows the working of the proximity sensor in a regular shaped fuel tank.

[0021] FIG. 8 shows the working of the proximity sensor in an irregular-shaped tank.

[0022] FIG. 9 shows the approximation logic to convert irregular shape tanks into small regular shape tanks.

[0023] FIG. 10 shows the improvement in the approximation with the increase in the number of points for the proximity sensor.

[0024] FIG. 11 shows the convergence of the calculated volume towards the actual volume of an irregular-shaped tank. The logic is tested on three different volumes.

[0025] FIG. 12 shows the exploded view of the user interface box.

[0026] FIG. 13 shows the electronic box that contains control and sensing circuits.

[0027] FIG. 14 shows the crab sensor placed inside the non-conductive hollow cylindrical tube.

[0028] FIG. 15 shows how the phenomenon of the Fano can be achieved in different resonant structures arrangements.

[0029] FIG. 16 shows the structure of the Fano based crab sensor.

[0030] FIG. 17 shows the nodal current in the crab sensor at three different frequency points.

[0031] FIG. 18 shows the frequency response and working of the crab sensor.

[0032] FIG. 19 shows a complete schematic block diagram to show the working of all blocks used in the sensor.

DETAILED DESCRIPTION

[0033] Aspects of the present invention and their advantages may be understood by referring to the FIGs and the following description. The descriptions and features disclosed herein can be used in but not limited to regular and irregular shaped fuel tanks used in automobiles and large storage tanks and liquids other than the fuel used in commercial or domestic applications. The invention discloses herein gives an accurate reading for both horizontal and inclined planes.

[0034] In broad terms, the property of linearity and scalability help to achieve much high sensitivity with a very small size. Planner integration was made possible by the innovation of microstrip structures. On-shelf integration can be achieved, which reduces both the complexity and device size. The microstrip structure behaves like an RLC open circuit with a resonant frequency depending on the host material's dimensions and permittivity. The permittivity of the air is 1, the permittivity of the fuel is 2.1-3, and the permittivity of water is 80. This massive difference in permittivity can detect mixing in the pure fuel and fuel level inside the fuel tank. The further details of the invention can be understood through the description and corresponding FIGs.

[0035] A fuel monitoring system 100 (which may be a level and quality monitoring system) is described in FIG. 1. The system 100 consists of multiple sensors working together to make a highly sensitive fuel quality and level monitoring system. A top is a user interface (UI) box 102 which consists of a display, status LEDs, and input buttons for giving instructions to various sensors. All electronics and controllers are hosted in an electronics box or enclosure 104. Subject to space and application, the Ul box 102 can be attached or separated from the electronics box 104 with the help of fasteners like screws. The electronics box 104 includes an ultrasonic sensor 106 for level and volume monitoring. The Ul box 102 and the electronics box 104 installs on a fuel tank. The sensing system 100 also consists of an optical proximity sensor 108. Movement of the proximity sensor 108 can be controlled by an input in the form of a knob 120.

[0036] A susceptible microwave crab sensor 112 made on substrate 110, is also included in the system 100 and is primarily used to detect quality of the fuel. Due to the ability to differentiate between air and fuel's permittivity, the tank's fuel level can also be detected with the crab sensor 112, which may provide more accurate detection. The crab sensor 112 is protected by a non-conducting rod 114.

[0037] A flow sensor 116 is installed at a fuel inlet. The flow sensor 116 measures the fuel volume as it enters the fuel tank. A lid sensor 118 detects the opening and closing of a lid of the fuel tank. The lid sensor 118 triggers the ultrasonic sensor 106 to check the fuel level when the lid is open. If the fuel level decreases, the system 100 may be configured to raise an alarm.

[0038] The system 100 measures the fuel volume in two different ways, e.g., with the help of the flow sensor 116 and with the help of an ultrasonic and proximity sensors 106, 108. An average of both volumes gives a more exact volume of the fuel inside the fuel tank. The system 100 is configured to crosscheck the volume calculated by the proximity sensor 108 and ultrasonic sensor 106 with the measured volume from the flow sensor 116. The combination of two-level monitors also detects a slope and avoids false readings in a gradient plane.

[0039] Referring to FIG. 2, the combination of the ultrasonic sensor 106 and crab sensor 112 provides accuracy in inclined planes as described in embodiment 200. The ultrasonic sensor 106 may incorrectly read the level when the tank is placed in an inclined or uneven plane. Usually, this issue is resolved by installing multiple sensors at different points, which increases the cost, complexity, and the area required to install the level monitoring sensor. The disclosed invention can measure an angle 204 and compensate for the effect of the inclined surface. The angle 204 can be measured if the difference between two levels 212 is known. When two points 208, 210 are on the same plane, the angle 204 will be zero, so no angle compensation is required. When the points 208, 210 are at different planes, the system 200 will calculate the angle and actual volume of the fuel inside the tank. A minimum threshold can be set below level 212 which is considered zero. For more accuracy, the threshold value may be as small as possible.

[0040] In embodiment 300, 302 is the top side of the user interface box 102. It contains a display 304, set button 306, options button 308, status led 310, and fault led 312.

[0041] Embodiment 400 shows the knob 120 used to change the angle of the proximity sensor 108. The knob 120 has an N-number of levels, and it controls the vertical movement of the proximity sensor 108. The 402 is the top side of the electronics box 104 [0042] Embodiment 500 shows the arrangement of the sensors. The electronics box 104 has a bottom side 504. The crab sensor 112 is placed at the centre of electronics box 104. The ultrasonic sensor 106 is placed at a distance from the rod 114 to sense the level and measure volume. The cut-out 502 for the proximity sensor 108 is opposite the rod 114.

[0043] A movement mechanism of the proximity sensor 108 is shown in embodiment 600. An IR (Infra-Red) transmitter 602 and IR receiver 604 are located at the left side of the proximity sensor 108. The proximity sensor 108 is fixed at one side of the knob 120 and free to move on the other side.

[0044] Embodiment 700 shows measurement of a volume of a regular fuel tank 702.

A distance to a sidewall of the fuel tank 702 can be measured by the proximity sensor 108. The proximity sensor 108 measures the distance from the wall at different points 704, 706, 708. When all the points 704, 706, 708 are found at the same distance (horizontal distance of the sensor 108 from the tank wall), the tank 702 is considered regular shaped, and similar points will be considered one.

[0045] The ultrasonic sensor 106 is configured to measure a distance 714 between it and a surface 712 of the fuel. This information, together with a known regular shape of the fuel tank 702, can be used to calculate or estimate a volume of fuel in the tank 702.

[0046] For an irregular-shaped tank 802, all points are considered as separate entries, and the volume of the irregular tank 802 is calculated based on its shape, as shown in embodiment 800. The proximity sensor 108 takes three different readings at three different points 804, 806, 808. When two points are at a different horizontal distance, the system 100 makes fragment-based calculations (starting with outer envelope 810). It divides the tank 802 into small fragments and sums up the values to calculate the total volume of the irregular tank 802. A fuel level 812 of the tank 802 is still sensed using the ultrasonic sensor 106.

[0047] The irregular tank 802 shown in embodiment 800 is fragmented into small regular-shaped tanks 902 (with outer envelope 904) as shown in embodiment 900. The accuracy of the calculated volume depends on the number of points 906, 908, 910 taken by the proximity sensor 108.

[0048] The embodiment of 1000 shows that how the sensor 108 approximates an irregular shape 1002 to a regular shape using a plurality of fragments 1004, 1006, 1008. When the proximity sensor 108 takes only one-point 1010, the approximation is less accurate, and the resulting volume will be much greater than the actual volume. But when the proximity sensor 108 takes readings at two points 1010, 1012, the resulting volume will be much closer to the actual volume.

[0049] The accuracy depends on the number of points taken for the approximation, as shown in the embodiment of 1100. The plots are calculated for four different volumes 1104. The volume 1106, 1108, 1110, 1112 converges to the actual value when the number of points 1102 taken by the proximity sensor 108 increases.

[0050] In embodiment 1200, a PCB 1202 is placed inside the user interface box 102.

The user interface box 102 and electronics box 104 provide a socket (or plural sockets) 1204 configured to receive a cable for connecting to one or more of the sensors 106, 112, 116, 118. This is illustrated in assembled condition in embodiment 1300 as socket 1302.

[0051] For quality monitoring, different methods are available. Capacitor-based fuel quality monitoring may be considered as low cost and the simplest of all available solutions. The liquid sample under test between the capacitive plates ("electrodes") acts as a capacitor's dielectric material. The drawback of such sensors is their poor spatial resolution, and they cannot detect minor variations in the level. The quality monitoring sensor disclosed may be a microwave resonant-based sensor.

[0052] Embodiment 1400 shows the crab sensor 112 inside the hollow plastic bar 1402 (air acts as substrate). Multiple similar crab sensors 112 are printed at a spaced apart distance from each other. Sensitivity increases multiple times by using multiple sensors 112 instead of a single one. When a plastic bar is placed inside the fuel sample, fuel will enter the hollow space in plastic bar, which means now substrate 1402 is also the fuel sample under test. This results in very high sensitivity. Lower layer of the substrate (plastic bar) 1402 is used as a ground 1404, and the crab sensor 112, which is a Fano-based sensor, is printed on an upper layer 110 of the substrate.

[0053] The Fano-based sensor 112 is made up of a microstrip line and is protected inside the rod 114 in the form of a cylindrical plastic case. As the Fano-based crab sensor 112 is susceptible to the dielectric close to the surface, the material of the cylinder will not touch the surface of the crab sensor 112. The crab sensor 112 disclosed in this embodiment has an ability to detect contamination and blends in pure fuel, e.g., if water-contaminated fuel is added inside the fuel tank. The water settles at the ground, and the resonant frequency of those sensors 112 covered or filled with water will be different from those who are covered/immersed with pure fuel.

[0054] The working phenomenon of the crab sensor 112 is microwave resonant based. An open stub resonator placed in the wave's path traveling through the microstrip gets absorbed at a particular frequency known as the resonance frequency. The resonance phenomenon achieved is similar to the resonance of RLC series-parallel circuit. As a result, very little or even no wave was received at the output port. When another RLC resonant circuit is introduced in parallel to the first RLC resonant circuit with the same resonance frequency, a transparency window is observed, which results in very high 0-asymmetric profile Fano resonance.

[0055] The same phenomenon holds in the case of microstrip based resonant structures. A Fano resonance is achieved by introducing an impedance mismatch 1506 in the signal travelling path through a straight microstrip line, as shown in embodiment 1500. A resonator 1508 includes ports 1502, 1504. The mismatched portion 1506 provides a transparency window in the absorption spectrum. The same phenomenon can be produced by placing slightly detuned resonant structures 1516, 1518 close to each other, adjacent a microstrip line 1512 with ports 1510 and 1514.

[0056] A crab resonator 112 is proposed in embodiment 1600. Two L-shaped or U-shaped chiral resonators 1606 and 1608 are placed at the centre of microstrip line 1610.

The L-shaped chiral resonators 1606 and 1608 are tuned close to each other to produce a high-Q transmission response. The crab resonator 112 defines ports 1602, 1064.

[0057] A nodal current at different spectral resonance frequency points is shown in embodiment 1700. When the length of the path 1702, 1704, 1722 (resonance below Fano) is almost equal to the quarter wavelength, the dominant current reflects, and minimum transmission is observed. The same case happens for path 1714, 1716, 1728 (resonance above Fano) for quarter wavelength, and no or minimum transmission is observed. At the resonance frequency (Fano resonance), which is the same for both L-shaped resonators, the current takes path 1708, 1710, 1724, 1726, 1710, 1712, resulting from which transmission is observed.

[0058] The normalised frequency response is shown in the embodiment 1800 as transmittance 1802 vs normalised frequency 1810. The dielectric constant of the fuel is 2.1. When no contamination is added, the crab sensor 112 resonates at its pre-tunned frequency 1806. When minor contamination is added into the pure fuel sample, the sample dielectric constant shifts from 2.1 to 2.0, the resonance frequency shifts right side 1808 in the frequency scale 1810. Similarly, when the resultant dielectric constant is 2.2, the resonance frequency shifts to the left side 1804 in the frequency scale 1810. This behaviour can be exploited to design a highly sensitive fuel quality monitoring sensor.

The dielectric constant of the air is 1. So, the resonant frequency will be shifted from its normal value in the absence of the fuel. This behaviour helps to detect the level of the fuel as well.

[0059] The complete system-level block diagram is shown in embodiment 1900. A control module in the form of a DSP (Digital Signal Processor) or microcontroller 1916 is the system's central control unit, and all the sensors 1926 send data to the microcontroller 1916. The microcontroller 1916 senses that the lid is open through lid sensor 118, 1914. The flow sensor 116, 1902 activates and measures the volume of the fuel poured into the fuel tank. The capacitive sensors 112, 1904 check the impurity in the fuel [0060] The proximity sensor 108, 1910 and ultrasonic sensor 106, 1912 are configured to measure the volume of the fuel. The microcontroller 1916 is configured to compare the volumes measured with both techniques. The microcontroller 1916 shows the measured parameters on display 1918. Throughout the whole process, a status LED 1 1920, and a status LED 2 1922 show the system's working and fault status, respectively. Measured, sensed, and/or calculated parameters are sent to a remote server or cloud-based recipient regularly via wireless transmission module 1924.

REFERENCES

[1] https://www uardmagic.corn/01-enoli2e products/04e-fuel-produ el-dafs2-1.htm [2] httos://www.seeedstudio.com/Grove-Ultrasonic-Distance-Senser.html?utrn source-bloc&utm medium-Oleg [3] httos:fielectronicshub.okloroductlisii-sr04-waterproof-ultrason c-distance-sensod [4] https://www.sparkfun.comiproducts/639 [5] https://www.seeedstudie.com/Grove.-80cm-Infrared-ProxirnitySensor. html?utrn source-bloq&utm medium-bloc] [6] https://endineerinq.eckovation,com/10-ir-senser-projects-that-you-can-do/ [7] https://www.seeedstudio.com/Seeedstudio-Grove-TF-MiniLiDAR.html?utm source-bloq&utm medium-blou [8] https://www.ereilly. comilibrarylviewlinternet-of-things/97817886274051e1d92619-1f31-42b7-a938- 10fd3192f445.xhtml [9] https://www.seeedstudie.corn/Grove-Time-of-Flight-Distance-SensorVL53LOX. html?utm source-bloo&utin medium-blo0 [10] Zhu, Junda, David He, and Eric Bechhoefer. "Survey of lubrication oil condition monitoring, diagnostics, and prognostics techniques and systems" Journal of Chemical Science and Technology 2.3: 100-115 (2013) [11] Tat, M. E., and J. H. Van Gerpen. "Biodiesel blend detection with a fuel composition sensor." Applied Engineering in Agriculture (2003).

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Claims (19)

1. CLAIMS1. A fuel monitoring system which includes: a control module configured to control sensors; an ultrasonic sensor mounted to a fuel tank and coupled to the control module, the ultrasonic sensor configured to measure or detect a fuel level of fuel in the fuel tank; and a Fano-based crab sensor mounted inside the fuel tank and coupled to the control module, the Fano-based crab sensor configured to monitor a quality of the fuel in the fuel tank.
2. 2. The fuel monitoring system as claimed in claim 1, in which the Fano-based crab sensor comprises a microstrip structure.
3. 3. The fuel monitoring system as claimed in claim 2, in which the microstrip structure comprises two chiral resonators which are L-shaped or U-shaped.
4. 4. The fuel monitoring system as claimed in claim 3, in which lengths of the two chiral resonators are the same, such that they resonate at the same frequency and, in combination, provide a Fano resonance with a high-Q factor suitable for fuel sensing.
5. 5. The fuel monitoring system as claimed in any one of claims 2-4, in which the microstrip structure is printed on a support structure.
6. 6. The fuel monitoring system as claimed in claim 5, in which the support structure is a hollow plastic structure which defines a cavity adjacent the microstrip structure, thereby allowing the fuel to fill the cavity and be sensed by the Fano-based crab sensor.
7. 7. The fuel monitoring system as claimed in any one of claims 5-6, in which support structure is provided inside the fuel tank such that the microstrip structure is entirely submerged within the fuel, the support structure acting as a substrate and the fuel acting as a superstrate.
8. 8. The fuel monitoring system as claimed in any one of claims 1-7, in which the microstrip structure includes plural sensing elements spaced a distance from each other.
9. 9. The fuel monitoring system as claimed in claim 8, in which the sensing elements are arranged at different operative heights, thereby to increase an accuracy and sensitivity of measurements.
10. 10. The fuel monitoring system as claimed in any one of claims 1-9, in which the ultrasonic sensor is installed at a top of the fuel tank.
11. 11. The fuel monitoring system as claimed in any one of claims 1-10, which includes a proximity sensor configured to measure or estimate a size of the fuel tank.
12. 12. The fuel monitoring system as claimed in claim 11, in which the proximity sensor is pivotally or hingedly mounted to the fuel tank, such that its angle relative to the fuel tank can be changed.
13. 13. The fuel monitoring system as claimed in claim 12, which includes an input mechanism coupled to the proximity sensor, the input mechanism configured to receive a user input and to translate that user input into an angular adjustment of the proximity sensor.
14. 14. The fuel monitoring system as claimed in claim 13, in which the input arrangement is a mechanical knob or dial configured to receive a mechanical input by hand from the user and to adjust an angle of the proximity sensor accordingly.
15. 15. The fuel monitoring system as claimed in any one of claims 11-14, in which the proximity sensor is embodied by an IR (infra-red) transmitter-receiver combination.
16. 16. The fuel monitoring system as claimed in any one of claims 1-15, wherein the fuel tank has an input and wherein the fuel monitoring system includes a flow monitoring device provided at an input to the fuel tank, the flow monitoring device being configured to measure an in-flow of fuel via the input into the fuel tank.
17. 17. The fuel monitoring system as claimed in any one of claims 1-16, wherein the fuel tank includes a cap, and wherein the fuel monitoring system includes a cap sensing device configured to measure or sense a state of the cap.
18. 18. The fuel monitoring system as claimed in any one of claims 1-17, which includes a communication arrangement configured to communicate one or more readings from the sensors to a remote recipient via a telecommunications network.
19. 19. The fuel monitoring system as claimed in claim 18, in which the remote recipient is a cloud-based computer system configured to store the one or more readings and, in response to the one or more readings triggering a reporting threshold, sending a reporting message to a designated recipient with details of the one or more readings.