FIELD OF THE INVENTION

The present invention relates to sensor system to measure fuel level, more particularly relates to measuring fuel level in automobiles.

BACKGROUND OF THE INVENTION

Existing capacitive type of fuel level sensor works based on the principle of dielectric. It works by measuring the change in capacitance between two conducting surfaces of inner and outer tubes profiles. The electronic signal conditioning circuit in the sensors measures the change in capacitance and converts this value to analogue output corresponding to fuel level in the tank. The output is further displayed as analogue signal or PWM signal.

The capacitance type fuel sensor form part of the capacitance to digital converter circuitry. As the capacitance varies, the output of the capacitance to digital converter circuitry will vary. The variation is measured and processed to compute the fuel level for any unknown dielectric constant of the fuel. Currently, the output is PWM signal proportional to the fuel level but analog output signal is also possible (as shown in FIG. 2).

Further in FIG. 2, Transient suppressor in the circuit suppresses the undesirable voltages detected at the supply input. Low dropout regulator regulates the input voltage to the desired voltage required for other integrated circuits to function. Capacitance to digital converter connected to the two sensors converts the measured capacitance values in to digital waveform. Microcontroller in the circuit reads the sensed values as a waveform and determines the fuel level using the algorithm embedded in it. Microcontroller outputs the fuel level calculated in the form of PWM.

These type sensors comprise non movable parts which ensure reliability of the entire system. Calibration feature is provided to compensate for the component tolerances while manufacturing and usage of all types of fuels. The above product can be calibrated at factory for any type of fuel. These sensors are applicable any type of fuel or any type of fuel mixture ratio.

Automobiles which use petrol as main fuel, alternative fuels such as ethanol, and ethanol mix fuels such as E10, E15, E20, and E85 are being used. These fuels can be mixed at any varying proportion by the user according to the availability, economy etc., These fuels vary in density as well as electrical properties which make the conventional fuel sensors feasible to measure the fuel level to the accuracy demanded by the end user.

Capacitance types of fuel sensors are available in the market but they are normally good for a specific type of fuel or for a specific type of fuel mixture. They often require calibration whenever the fuel type or fuel mixture ratio is changed.

FIG. 1 illustrates existing method adopted for measurement of fluid level, wherein 1-Tank; 2-Liquid; 3-Outer tube; 4-Central electrode; 6-Measuring device.

OBJECTS OF THE INVENTION

The main object of the present invention is to develop a system which automatically measure electrical property of the fuel and automatically learn the type of fuel as well as the volumetric ratio mix of the fuel in vehicles.

Yet another object of this invention is to measure the composite electrical property of the fuel in the fuel tank and to indicate the correct volume data of the fuel present in the fuel tank.

STATEMENT OF THE INVENTION

Accordingly, the present invention provides for a system to measure dielectric constant and fuel level, the said system comprising plurality of sensor elements disposal inside container (fuel tank) at pre-determined heights or plurality of sensor elements of different profiles , a capacitance to digital converter-module connected to each sensor excites the sensor element measures the capacitance value and produces a proportional signals, a microcontroller to process the signal output from the capacitance to digital converters connected to each sensing element and to generate output signal proportional to the level of the fuel in addition to above , the microcontroller is also confirmed to compute the composite dielectric constant of the fuel mix which can be output as digital data .The same microcontroller can also be configured to function as capacitance to digital converter or it can be configured using a separate electronics circuitry.

Since the objective of this invention is to measure both composite dielectric constant as well as the level of the fuel mix, triangulation methodology is adopted for computation. The required computational process is also carried out using said microcontroller with suitable application programme.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The features described in this disclosure are set forth with particularity in the appended claims. These features and attendant advantages will become apparent from consideration of the following detailed description, taken in conjunction with the accompanying drawings. One or more embodiments are now described, by way of example only, with reference to the accompanying drawings wherein like reference numerals represent like elements and in which:

FIG. 1 shows an existing method adopted for measurement of fuel level,

FIG. 2 shows block diagram illustrating the measuring of fuel and computing dielectric constant,

FIG. 3 shows various arrangements of sensor elements to measure dielectric constant and level of fluid/fuel, case 3 shows schematic diagram of sensor elements to illustrate the triangulation method according to instant invention.

DETAILED DESCRIPTION OF THE INVENTION

The main embodiment of present invention relates to a system to measure dielectric constant and fuel level, said system comprising plurality of sensor elements disposed inside container at predetermined heights; at least one capacitance to digital converter connected to each sensor element to receive input signals from the sensor elements to produce signals; a microcontroller being adopted to receive the signals from the capacitance to digital converter to generate output signals proportional to the fuel level and fuel mixture composition; a microcontroller configured to compute composite dielectric constant of the fuel and the fuel level.

In still another embodiment of the present invention the output signals generated by the microcontroller are preferably Pulse Width Modulated (PWM) or analog signals.

In yet another embodiment of the present invention the sensor elements are arranged asymmetrically profiled and are preferably two in number.

In yet another embodiment of the present invention the container is preferably a fuel tank.

In yet another embodiment of the present invention the system is capable of measuring dielectric constant of combination of alternate fuels used in an automobile.

Another embodiment of the present invention provides for a method to measure dielectric constant and fuel level, said method comprising acts of measuring capacitance of plurality of sensor elements by generating output signals proportional to fuel level and fuel mixture composition; and computing effective capacitance using triangulation method to measure dielectric constant and fuel level.

Yet another embodiment of the present invention provides for an automobile comprising a system to measure dielectric constant and fuel level, said system comprising plurality of sensor elements disposed inside container at predetermined heights (Fig 3 case 1) or asymmetrically profiled sensor elements arranged as shown in case 3 of figure 3; at least one capacitance to digital converter connected to each sensor element to receive input signals from the sensor elements to produce signals; a microcontroller being adopted to receive signals from the capacitance to digital converter to generate output signals proportional to the fuel level and fuel mixture composition; a microcontroller configured to compute composite dielectric constant of the fuel and the fuel level.

The proposed method ensures the auto learning capability of any fuels used in automobile field. This system also works based on the electrical properties of the fuels. The new design includes two level sensors of different dimensions. The sensor detects efficiently & effectively two parameters namely, the dielectric constant as well as the height of the fuel. Hence for a specific fuel level, these sensors will give out different capacitance values. By use of triangulation techniques, these variables are computed and thus the fuel level signals are sent out of sensor as proportional DC Voltage or as proportional PWM signal.

The sensor is also carry out nominal averaging to give a fairly stabilized output under various driving conditions.

This system is well suited for the vehicle system using multi fuels. The proposed new method in this invention uses two capacitance sensors like as described above which are stacked in such manner that one is placed asymmetric to another as shown in FIG 3 case 3.

Triangulation method

Referring to FIG. 6, let SI and S2 be the two sensor elements. Capacitance values varies based on the dielectric constant of air, fuel and area of the two sensor elements.

By mathematical calculation, the fuel level (h) and dielectric constant (Er) of the fuel by using the below equations are determined.

h=L(l-(C2-Cl)/(Cl-K:2-2ALA2))

Er= 1 +((C 1+C2-2AL A2)/(2ALh))

where A - Constant, L- Length in mm, h- Fuel level in mm, CI-Capacitance value of Sensor element 1 and C2-Capacitance value of Sensor element 2.

FIG. 2 illustrates schematic diagram of tank comprising sensors. Any combination of alternate fuel filled in a tank has a composite dielectric constant. Our objective of using this sensor is to measure the composite dielectric constant as well as the height of the fuel level. Since two variables are to be found that two sensors are used in this invention. The effective capacitance of the sensors depends on the level of fuel filled in the tank. Since these sensors are asymmetrical in terms of dimensions, they produce different capacitance value. By triangulation techniques the effective capacitance value is calculated as in the above method.

The capacitance type fuel sensor form part of the capacitance to digital converter timing circuitry. As the capacitance varies, the frequency output of the capacitance to digital converter will vary (as shown in FIG. 5). The frequency measured from capacitance to digital converter units is processed using controller to compute the fuel level. The controller frequently monitors the change in frequency and gives out the output in terms of PWM proportional to the fuel level. This type of sensor is well suited for vehicle using multi fuels.

The invention has been described in connection with its preferred embodiments. However, it is not limited thereto. Changes, variations and modifications to the basic design may be made without departing from the inventive concepts in this invention. In addition, these changes, variations and modifications would be obvious to those skilled in the art having the benefit of the foregoing teachings. All such changes, variations and modifications are intended to be within the scope of this invention.

The technology of the instant Application explained with the examples should not be construed to limit the scope of the invention.

We claim:

1. A system to measure dielectric constant and fuel level, said system comprising:

a. plurality of sensor elements disposed inside container at predetermined heights; or
two asymmetric profiled sensor elements placed at same height;

b. at least one capacitance to digital converter ICs connected to each sensor element to receive input signals from the sensor elements to produce signals;

c. a microcontroller being adopted to receive the signals from the capacitance to digital converter ICs to generate output signals proportional to the fuel level and fuel mixture composition;

d. a microcontroller configured to compute composite dielectric constant of the fuel and the fuel level; and

e. an algorithm implemented in Software residing inside the micro controller to compute composite dielectric constant and fuel level of Fuel mix using Triangulation techniques.

2. The system as claimed in claim 1, wherein the output signals generated by the microcontroller are preferably Pulse Width Modulated (PWM) or analog signals.

3. The system as claimed in claim 1, wherein the sensor elements are arranged asymmetrically and are preferably two in number.

4. The system as claimed in claim 1, wherein the container is preferably a fuel tank.

5. The system as claimed in claim 1, wherein the system is capable of measuring dielectric constant and level of combination of alternate fuels used in an automobile.

6. A method to measure dielectric constant and fuel level, said method comprising acts of:

a. measuring capacitance of plurality of sensor elements by generating output signals proportional to fuel level and fuel mixture composition; and

b. computing effective capacitance and using triangulation method to measure dielectric constant and fuel level.

7. the method as claimed in claim 6, wherein the dielectric constant of the fuel mixture is measured by the sensor element.

8. An automobile comprising a system to measure dielectric constant and fuel level, said system comprising:

a. plurality of sensor elements disposed inside container at predetermined heights,

b. at least one capacitance to digital converter connected to each sensor element to receive input signals from the senior elements to produce signal,

c. a microcontroller being adopted to receive the signals from t capacitance to digital converter to general output signals proportional to the fuel level and fuel mixture composition, and

d. a microcontroller configured to compute composite dielectric constant of the fuel and the fuel level.