Volume in Fuel Tanks

Technical Field

The present invention pertains to electrical sensors measurement for accurate evaluation of a fuel liquid level/amount inside fuel tanks, particularly to electrical capacitive sensors, which are installed inside fuel tanks and are remotely controlled by external controller via Bluetooth Low Energy communication Method (BLM/BLE).

Background

Accurate measurement of fuel amount/level inside small and large fuel tanks of cars, trucks and other vehicles is a highly important issue with both economic and safety aspects. These issues are not sufficiently resolved in the current apparatuses, which are based on floating potentiometers which are built-in inside fuel tanks of cars, trucks and other vehicles. This problem is highly pronounced in large fuel tanks, which are installed inside large vehicles. In this case, the car owners/drivers can benefit from accurate fuel tank sensors, enabling them to supervise the fuel amount accurately, eliminating potential economic losses due to misevaluation of the fuel amount inside the hosting fuel tank.

To solve these issues, an extensive study and development of electrically based fuel gauging systems and sensors has been performed. These sensors comprise capacitance probes, which are located inside the vehicle's fuel tanks. Exemplary cases of such sensors are based on capacitive sensors. Such capacitive probes/sensors for fuel amount measurement are disclosed in US patents Nos. 8,281,655 and 7,475,665 for fuel gauging system utilizing a digital fuel gauging probe and a capacitance-based fluid level sensor, respectively. Other prior art such as CN 202485751 and US patent No. 4,806,847 disclose capacitive probes/sensors including a corresponding method for dielectric liquid level measurements and a dielectric liquid level sensor. The disclosed corresponding method is employed to measure various types of car liquids such as transmission oil and other types of oils, which are used for the operation of the vehicles engine, power transmission and other essential systems. Almost all prior arts disclose capacitive probes/sensors that consist of two concentric metallic

plates/electrodes, which are separated by an empty volume/medium between them. The capacitive probes/sensors are installed along the fuel tank's vertical axis, which is oriented along the normal direction with respect to the fuel liquid surface level.

In this design, the particular important design issues are the location and configuration of the capacitive probes/sensors inside the fuel tank and the architecture of their electrical interface with the vehicles control and monitoring unit. Various types of such designs comprise different configurations of electrical interfaces and attached probes and sensors are disclosed in previous publications. A detailed study of these publications shows that the conventional electrical interfaces, which mitigate between the capacitive electrical probes and the car control and monitoring unit, limit the related probe position to particular location, related configuration and architectural design. As a result of these designs, one must consider that both the probes/sensors and its attached electrical interface are exposed to the car environmental time- varying conditions, and as a result they are constantly subjected to thermal and mechanical stresses which are applied by the car surrounding conditions. This can potentially result in a relatively high degradation processes, resulting in malfunction, disfunction or degraded performance of both the electrical interface and the attached capacitive probe/sensor.

Furthermore, these designs are required to meet strict regulations and safety conditions in order to avoid electrical discharges, which may damage the fuel tank or result in fire or explosion inside the fuel tanks. These regulations refer to the electrical design and required specifications of both the capacitive probes/sensors and the electrical driving circuits, which in addition must be electrically isolated from the fuel tank and fuel liquid.

KR 20170078336 relates to a fuel drain plug capable of detecting a fuel residual amount and a system for detecting it in fuel tanks. This system includes a control unit that determines if the vehicle is in a running state based on its speed and engine RPM, a tilt sensor for sensing the flow rate of fuel in the fuel tank and a calculator for calculating the remaining fuel amount. The vehicle speed and fuel amount data are stored and transmitted to an external device. US 2010/0251816 describes a fuel measurement system that utilizes one or more digital electrical capacity based probes for measuring fuel amount in a fuel tank of a vehicle. The probe is based on an electrical circuit and incorporates a digital circuit. The digital circuit converts the capacitance value to a digital value and communicates the measured data over a digital bus to a fluid gauging computer via a data bus.

These strict regulations and safety constraints force the design of the electrical capacitive sensors to operate at very low operational voltage values in certain allowed ranges and values, which correspond to certain allowed ranges and values of electrical fields. Hence, these particular designs are carefully inspected and tested in order to meet the reliability and safety regulations and constraints, resulting from the fuel tanks and vehicles properties.

It is, therefore, an object of the present invention to provide a capacitive electrical probe/sensor with a smart, safe and highly reliable attached control interface, which meets the capacitive probe/sensor reliability and safety regulations requirements.

It is yet another object of the present invention to provide a capacitive electrical probe/sensor with interface, which enables proper and easy installation, which ensures reliable and safe operation of the capacitive probe/sensor.

It is yet another object of the present invention to provide a capacitive electrical probe/sensor design, which sustains highly reliable fuel amount measurement under applied thermal and mechanical stress.

It is yet another object of the present invention to provide a probe/sensor with a design with electrical capacitive probe/sensor, which sustains highly reliable measurement values and a simple calibration procedure of fuel amount considering various parameters such as fuel type, environmental conditions, temperature range, contamination levels and other parameters. Further, the probe/sensor sustains constant, gradient or other variations, which are applied by the car surrounding conditions. It is yet another object of the present invention to provide a capacitive electrical probe/sensor design, which yields a high accuracy indication of the fuel amount inside the fuel tank.

These parameters may pose absolute constant values, timely varying values or geometrical varying values across the fuel tank.

Summary

In one aspect, the present invention pertains to accurate electrical sensors of fuel fluid inside a fuel tank.

In another aspect, the present invention pertains to fuel fluid electrical sensors which are remotely controlled by Bluetooth Low-voltage Energy Method (BLE/BLM) remote means ensuring a low voltage operational working range and safe operational range to correspond regulation constraints.

In still another aspect, the present invention pertains to highly reliable fuel probe/sensor, which is configured to sustain accurate and reliable measurements under varying electrical and mechanical stresses under varying environmental conditions.

Method

In one aspect of the present invention, the electrical capacitive fuel sensor is remotely controlled by BLE/BLM low voltage communication method that eliminates the need for physical electrical interface and further enabes to position the electrical capacitor in various positions and configurations inside the fuel tank.

In one embodiment of the present invention, the cylindrical capacitive fuel sensor is remotely activated by a magnet, which is attached to the capacitor in close proximity to one of its sides. The attached magnet is remotely activated by a Bluetooth

Electromagnetic (BLE) signal, using the Bluetooth Low energy Method (BLM), thus enabling to remotely activate the capacitive fuel sensor and measure the liquid height/amount. In still a further embodiment, the disclosed BLE/BLM system is designed according to the following guidelines and design rules:

• The integration of the capacitive fuel sensor inside the car fuel tank is designed to enable optimal capacity measurements, using a predefined resistor and measuring the high time value required for charging to the capacity value. Furthermore, a timer is used when charging begins and stops when the capacity value is reached;

• A dedicated mobile application is designed to guide the user to update the capacity values that are measured into percentage values of fuel in a tank;

• A calibration of the capacitive values versus the fuel percentage amount is done in different resolutions according to predefined accuracy demands;

• The apparatus is included with an internal battery voltage source of 3 V;

• The voltage danger operational values are lowered to minimum values,

particularly at high values. This is done by fitting this high voltage range of value to significantly lower values and by electrically isolating the connection between the capacitor and the resistors;

• The temperature is constantly measured in order to estimate the fuel volumetric change used for accurate evaluation in compared to it;

• The product is wrapped in a fire & fuel immune plastic layer;

• Unique Bluetooth protocol that includes data security and encryption;

• The Bluetooth communication is used to send the fuel's data as a converted value once the peripheral unit, identified by its characters based ID, is connected with the central remote control unit.

Apparatus

In one preferred embodiment, the capacitive BLE/BLM remote control system comprising:

a remote controlled BLE/BLM transceiver;

an electrical capacitive fuel sensor apparatus which is installed inside a fuel tank at the bottom of the fuel tank with data link connection channel with the

BLE/BLM transceiver;

a fuel tank with fuel measurement apparatus attached to its original based float; an additional starlink unit comprising software and BLM/BLE transceiver components, which are installed inside the vehicle control system; and

communication means with the controlled BLE/BLM transmitter which is attached to the electrical capacitive fuel sensor apparatus.

In one embodiment, said electrical capacitive fuel sensor apparatus is inserted through a hole drilled at the bottom of the fuel tank and installed at the bottom of said fuel tank. In another embodiment, the electrical capacitive fuel sensor apparatus is inserted through a fuel tank draining outlet and installed at the cover of the fuel tank draining outlet or at the bottom of the fuel tank.

In a further embodiment, the data link communication channel with said capacity measurement device, labeled as the capacitive fuel sensor apparatus is done through a Bluetooth transmitter via a BLM/BLE secured communication channel and a related protocol. In yet a further embodiment, the data link between the capacity

measurement fuel sensor and the Bluetooth transmitter can be done via wired or wireless means.

In yet a further embodiment, the capacitive fuel sensor apparatus publishes itself via a specific ID, the starlink unit identifies it as an ERM sensor with a capacitive sensing measurement capabilities. In this case, a secured encrypted connection is established between starlink unit and the capacitive fuel sensor. The capacitive fuel sensor apparatus utilizes the BLM/BLE secured communication channel to transmit the capacitive measured data to the starlink unit. In yet a further embodiment, the calibration procedure is done by using the capacitive fuel sensor apparatus measurement data and the actual measurement of fuel amount is done with a mobile application, which is installed on the user mobile phone or any other mobile means. This is done by reading the fuel amount data inside the fuel tank in each filling event, wherein this data can be read by the original based float fuel measurement apparatus and or by the fueling pump apparatus. In this case, no additional special complicated mathematical calculations are required. In its installed position, the capacitive fuel sensor is partially sunk inside the fuel tank, wherein its capacitive fuel sensor separation volume is partially filled with the fuel liquid where its remaining volume is filled with air. Generally, these sensors are designed to be highly sensitive to variations in the fuel liquid level inside the fuel tank, wherein their capacitance proportionally increases with the fuel amount inside the fuel tank. Furthermore, for accurate measurements these probes are designed to sustain accurate measurements under varying environmental conditions, considering as well other multiple parameters. Such parameters can be the fuel type, the contamination level of the fuel liquid inside the fuel tank and the fuel's temperature absolute value including temporal and real space variations. Further variations can include the time varying fuel temperature which is driven by external thermal impacts, induced stray capacitance impacts and other parameters. This can result in dielectric variations in the fuel substance, and hence bias the related sensors capacitive values. Furthermore, such electrical capacitive probes and sensors must be designed to meet the strict regulations and safety conditions of the fuel tank, which is embedded inside the vehicle. These regulations are set in order to avoid electrical discharges which may damage the fuel tank or which may result in explosions and fire inside the fuel tank. As a result, these strict regulations and safety constraints force the electrical capacitive fuel sensors to be designed to operate at very low operational voltages and allowed ranges of electric fields. This includes the design of the capacitive fuel sensor electrical design, including the electrical driving circuits which in addition must be electrically isolated from the corresponding fuel liquid and from the fuel tank.

Other important design issues are the location and configuration of the capacitive fuel sensors inside the fuel tank and the architecture of their electrical interface with the vehicle’s control and monitoring unit. The electrical interface of the capacitive fuel sensors is exposed to the car environmental time- varying conditions and as a result is constantly subjected to thermal and mechanical stresses which are applied by the car surrounding environmental conditions. This can potentially result in a relatively fast degradation process, malfunction, disfunction or degraded performances of the attached capacitive fuel sensor. Various types of such electrical interface for these probes and sensors are disclosed in several prior arts. Furthermore, from a study of these prior arts, it appears that the conventional electrical interfaces, which mitigate between the capacitive electrical probes and the car control and monitoring unit, limit the related probe position, configuration and architectural design. Hence the electrical interface between the capacitive fuel sensor/probe must be designed very carefully in order to meet the reliability, safety and regulation constraints of the fuel tank of the vehicles.

In one embodiment, the capacitive fuel sensor system comprises

a remote control capacitive fuel sensor system comprising:

a capacitive probe composed of a hollow double electrode capacitor with two plates/electrodes, which are inserted into the fuel tank;

a BLE communication module which enables to remotely execute capacitance measurement of the capacitive sensor/probe located inside the fuel tank;

a plurality of electrical circuits comprising:

at least one electrical circuit which can support the operational voltage of the capacitive sensor/probe and a measuring module;

at least one electrical circuit which can support the control unit of capacitive probe including all of its logic and analog components;

at least one electrical circuit which can support BLE/BLM communication module which is controlled by car control unit via Bluetooth low voltage communication protocol.

The capacitive fuel sensor comprises internal and external cylindrical plates, wherein at its installed/inserted position, is fully or partially sunk inside the fuel tank and filled with the fuel liquid to a certain height, which correlates with the fuel liquid height. In this design, the fuel liquid fills the empty volume between the cylindrical plates of the capacitor along its vertical main axis up to the liquid height in the tank, thus modifying its average dielectric constant and electrical properties accordingly and as result the value of its average total capacity.

At the installed/inserted position, the capacitive fuel sensor inside the fuel tank which is fully or partially sunk and filled with the fuel liquid to a certain height, correlates with the liquid height inside the fuel tank. The liquid fills the empty volume between the cylindrical plates of the capacitor along its vertical main axis up to the liquid height, thus modifying its average dielectric constant and electrical properties, such as the value of its average total capacity.

In a further embodiment, the remote electrical capacitive fuel sensor is designed for accurate evaluation of the liquid fuel amount inside the fuel tanks. In still a further embodiment of the present invention the capacitive fuel sensor is a double electrode shape cylindrical hollow capacitor comprising internal and external cylindrical plates, which is inserted into the fuel tank.

In a further embodiment, the capacitive fuel sensor is a double electrode/plate shape cylindrical capacitive sensor, which is remotely activated by a magnet, which is attached to the capacitor in close proximity to one of its sides. The attached magnet is remotely activated by a Bluetooth Electromagnetic (BLE) signal, using the Bluetooth Low energy Method (BLM), thus enabling to remotely activate the capacitive sensor and measure the liquid height/amount.

In a further embodiment, the remote control capacitive fuel sensor system comprises a temperature sensor which constantly measures the temperature in order to estimate volumetric change of the fuel upon filling, burning and drainage. In yet a further embodiment, the capacitive fuel sensor is controlled by the BLE communication wherein the control signal is sent wirelessly by an external cellular mobile, a tablet or other mobile remote apparatus/device comprising Bluetooth wireless transceiver. This enables low voltage operation, which is also necessary to eliminate driven electrically induced damages to the fuel tanks.

In yet a further embodiment, the capacitive fuel sensor is mounted on the fuel tank filling inlet, or the capacitive fuel sensor of the present invention is configured to be mounted on the fuel tank drainage outlet at the internal side of its closure plug. These configurations integrate smoothly with any type of fuel tank and do not require any drilling or screwing operations to fix the sensor to the tank walls. With respect to the traditional sensors, the assembling and disassembling of the sensor inside the fuel tank drainage plug is rather smooth and enables quick and easy accesses for maintenance purposes. Capacitive sensor regulation constraints inside fuel tanks

The remote capacitive fuel sensor experimental method is based on low operational voltage range which is designed to meet the approved regulation values of voltage in small or large fuel tanks. In this design, high operational voltages inside fuel tanks of electrical capacitive fuel sensor can yield in mechanical, electrical or chemically driven damages to the fuel tank and its hosting vehicle. It may further result in explosion or ignition and a subsequent burning of the fuel inside the fuel tank and creation of damages to the fuel tank or its hosting vehicle. As an example for small/large size fuel tanks, the maximum values of the applied operational voltages are regulated and do not exceed 3 V. For large tanks, a 28V operational voltage may induce a much higher voltage of 150 V resulting in potential damage to the fuel tanks.

In a still further embodiment, the capacitive fuel sensor is electrically and chemically isolated from the fuel tank walls and liquid content. This is done to avoid unwanted electrical discharges or electrical induction of the capacitive fuel sensor on both the fuel tank walls and fuel liquid, which may result in ignition or explosion of the fuel or cause any other chemical or mechanical damage to the fuel tank.

Measurement accuracy resolution

Another main advantage of the capacitive fuel sensor of the present invention is its high accuracy indication of the fuel amount inside the fuel tank. Currently, the most common capacitive fuel sensors are based on a floating element on the surface of the fuel liquid. This yields in insufficient and poor accuracy of its analog/digital scale and resolution. As a result, the fuel pointer and indicator does not correlate well and does not indicate the correct state of fuel level inside the fuel tank. The fuel pointer drops only after a significant portion of fuel leaves the tank after consumption. The poor correlation between the amount of fuel in the tank and the fuel indicator pointer is intensified in large vehicles with large volume fuel tanks such as trucks and buses. These large fuel tanks are generally equipped with the traditional capacitive fuel sensors with a small scale indication display means and low resolution. Hence, these vehicles suffer from a relatively higher inaccuracy in the reading of the amount of fuel with an analogue capacitive sensor. This results in high uncertainty and insufficient indication of the full amount or fuel loss and a subsequent large amount of fuel waste.

As an example, the floating based element pointer divides the fuel tank to 20 notches/sub-divisions per scale. When filling a large fuel tank with volume of 400 litters, an amount of 40 litters from a tank maybe absent or stolen without any indication to the driver. In contrast, the remote capacitive fuel sensor of the present invention enables high resolution indication with 300 or more notches/sub-divisions per a given fuel tank. This leads to a highly sensitive linear correlation between the capacitive fuel sensor resistance and the amount and volume of the fuel inside the tank.

Capacitive fuel sensor design goals

One main feature of the present invention is wireless BLE communication design especially due to the low voltage operation bias which must meet the vehicle's fuel tank regulation constraints of such wire or wireless capacitive fuel sensor inside a fuel tank. Generally such sensor design must address the following issues

- Fuel impedance and dielectric constant variations as a result of contamination, different fuel type, fuels mix with different physical

Compensator apparatus or method for the fuel temperature variations including temperature gradients inside the fuel tank that relate to reliability issues of the capacitive fuel sensor and its supporting/driving electrical circuits under extreme temperature bias and temperatures variations inside a fuel tank

- Parasitic/strays capacitance, which can be minimized by correct sensor

geometrical design chip design, ensuring high precision fuel capacitance measurements

- Electrical isolation to ensure proper and safe operation under the fuel tank

regulation constraints.

The following describes particular examples and embodiments of the present invention with reference to the accompanying drawings and without limiting the scope of the present invention. Brief Description of the Drawings

Fig. 1 shows a schematic diagram of the electrical capacitive fuel sensor, which is remotely controlled by a BLE/BLM.

Detailed Description of the Drawings

Fig. 1 shows a schematic diagram of the capacitive BLE/BLM remote control system (100) comprising the electrical capacitive sensor (1) and the remote controlled BLE/BLM communication system (2). The configuration of the fuel tank and the capacitive BLE/BLM remote control system (100) is shown in Fig. 1. As shown, the related configuration comprises a fuel tank (6) with its original cover (5) and attached original float based fuel measurement apparatus (4). The capacity measurement device (1), labeled as a capacitive fuel sensor apparatus, is attached to the capacity Bluetooth transmitter (2) which is inserted through a drilled hole (3) made at the bottom side of the fuel tank (6). In this case, the capacitive fuel sensor's transmission data is sent through the Bluetooth transmitter (2) via a BLM/BLE communication protocol. In another embodiment, the electrical capacitive fuel sensor apparatus (1) is inserted through the fuel tank draining original outlet (not shown) and installed at the bottom original draining outlet or on the cover of the fuel tankof the fuel tank.

In a further embodiment, the capacitive BLE/BLM remote control system and configuration further comprise an additional starlink unit, comprising software and BLM/BLE transceiver components, which are installed in the vehicle control system. The sensor publishes itself, via a specific ID, and once a secured encrypted connection is established between starlink and the sensor, the starlink unit identifies it as an ERM's sensor with capacitive sensing measurement capabilities. The sensor (1) utilizes the BLM/BLE secured communication channel to transmits the measured data to starlink unit. The calibration procedure of the sensor capacitive measurement is done by a mobile application installed on the user mobile phone or any other mobile means. The mobile application utilizes the received data measured by the capacitive sensor apparatus (1) and the fuel amount data, which is measured by its original floating apparatus (4) inside the fuel tank in each filling event. In this case, the fuel amount data is read by the original based float fuel measurement apparatus (4) and/or by the fueling pump system.