BR102012004011A2 - ELECTRONIC LIQUID LEVEL METER WITH DIELETRIC CONSTANT DETECTION SENSOR - Google Patents

Abstract

"ELECTRONIC LEVEL LEVEL METER WITH DIELETRIC CONSTANT DETECTION SENSOR" ELECTRONIC RESERVOIR LEVEL METER MEANS THE FOLLOWING COMPONENTS; CONNECTOR (1) TWO OR THREE WAY; SEALING GASKET (2) POSITIONING BETWEEN TOP COVER (4) AND LOCAL SURFACE WHERE THE METER WILL BE INSTALLED; EXTERNAL METAL PROFILE (3) WITH SIDE SLOT FOR EASY LIQUID FLOW AND ACTING AS EXTERNAL ELECTRODE IN THE MEASURING SYSTEM; TOP COVER (4) COVERING THE ELECTRONIC PART OF THE METER; INTERNAL METAL PROFILE (5) ACTING AS INTERNAL ELECTRODE OF THE SYSTEM; SENSOR FOR DETECTION OF DIELETRIC RESERVOIR LIQUID CONSTANT (6). The reservoir liquid level meter comprises the following blocks; CONNECTOR (1): CONNECTION BETWEEN THE INTERNAL CIRCUIT OF THE METER (4) AND THE PERIPHERALS; OUTPUT CIRCUIT (41) CONDITIONING THE READING SIGN; POWER SUPPLY (42) CONVERTING THE BATTERY VOLTAGE LEVEL; LIQUID LEVEL METER (43): USED BY THE CPU (44) TO DETERMINE THE RESERVOIR LIQUID LEVEL IN WHICH THE METAL PROFILE (3 AND 5) IS IMMERSED; CENTRAL PROCESSING UNIT (44): COLLECT DATA FROM ALL OTHER BLOCKS AND RELATED TO THEM; TEMPERATURE COMPENSATION (45): Used by CPU (44) to compensate for TEMPERATURE VARIATION; IS USED FOR MEASURING AN INTERNAL REFERENCE COMPONENT SUSTAINABLE FOR TEMPERATURE VARIATION; INSTRUMENT PANEL (7): RECEIVES EQUIPMENT OUTPUT SIGNAL AND CONVERTS IN VISUAL DISPLAY OF RESERVOIR'S LIQUID LEVEL; AUXILIARY ELECTRODE (6): POSITIONED ON ELECTRONIC METER BASE AND CORRESPONDS TO TOP OF RESERVOIR, BEING RESPONSIBLE FOR DETECTION OF LIQUID WHEN RESERVOIR IS FULL AND SENDING A CPU (44) WHICH INTERPERSES "

Description

"ELECTRONIC LIQUID LEVEL METER WITH DIELETRIC CONSTANT DETECTION SENSOR"

The present invention relates to an innovative electronic reservoir liquid level meter which is provided with a liquid dielectric constant detection sensor which informs a new calibration as a function of changing the characteristics of the liquid.

There are currently several liquid level gauges on the market, mostly applied for fuel level measurement in vehicle reservoirs. With the evolution of these level meters, mechanical displacement systems are no longer used to measure liquid level, which have been replaced by solutions with capacitive or resonant technology, such as those cited in US 6,935,173. Through a sensor (fixed rod) the fuel level analysis is performed in a reservoir. For accurate analysis it is necessary that the meters identify the dielectric constant of the liquid being measured. For example, a gauge calibrated for diesel dielectric constant when measuring water, whose dielectric constant differs from diesel, will have inaccurate measurement.

Another example is the use of biodiesel in vehicles. Currently in the market there are several types of biodiesel, for example, B-20 (20% biodiesel and 80% diesel) and B-50 (50% diesel and 50% biodiesel), among others. Some agricultural machines already operate on B-100 fuel (100% biodiesel). These biodiesel dosing variations in diesel cause variations in the liquid's dielectric constant, that is, state of the art meters have measurement errors when subject to variations in the nature and composition of the liquid to be measured.

A known way to solve the liquid level reading errors caused by varying its dielectric constant is to provide a liquid level meter already calibrated for a given dielectric constant of a specific liquid. However, this meter does not operate precisely with other types of liquids, which makes it less versatile.

Another known way to solve the liquid level reading errors caused by varying its dielectric constant is to provide a key level or potentiometer to allow the operator to adjust the. meter output (directed to the instrument panel) in relation to the amount of liquid in the reservoir. In this way, whoever is handling these control interfaces adjusts the dielectric constant of the liquid being analyzed. However, this solution requires specific operator circuits, skill and technical knowledge, and is subject to the intrinsic failures of human interference.

It is therefore an object of the present invention to use an electronic meter

The liquid level meter incorporates a dielectric constant liquid detection sensor that informs the electronic liquid level meter central processing unit when the reservoir is full, regardless of the liquid type. With "full tank" information, the electronic meter can adjust its output to the instrument panel, thus ensuring accurate reading.

The advantage of the invention over state of the art meters is that it does not require human interference to be adjusted, thus reducing the margin of error. Every time the reservoir is filled the electronic system automatically calibrates itself to the dielectric constant of the current liquid, thus ensuring accurate reading.

The electronic liquid level meter with dielectric constant liquid detection sensor of the invention is now described in detail based on the attached drawings, which illustrate a preferred constructivity not to be construed as limiting the invention:

Figure 1 - perspective of the electronic liquid level meter that incorporates the

dielectric constant detection sensor of the invention; Figure 2 - front view of the electronic liquid level meter with the sensor of the invention;

Figure 3 - bottom view of the electronic liquid level meter with the sensor; Figure 4 - block diagram of the liquid level meter with the sensor; Figure 5 - Liquid level meter circuit with the sensor of the invention; Figure 6 - Flowchart of the electronic meter control software incorporating the sensor of the invention.

Figures 1 to 3 illustrate the electronic liquid level meter.

reservoir comprising:

- connector (1) which may be three-way (voltage output signal) or two-way (pulsed signal);

- gasket (2) which is positioned between the top cover (4) and the surface of the place where the meter will be installed;

- external metal profile (3) with a side slot for easy liquid flow and acting as an external electrode in the measuring system;

- top cover (4) housing the electronic part of the meter;

- internal metal profile (5) acting as the internal electrode of the measuring system;

- sensor for detecting the dielectric constant of the liquid supplied to the reservoir (6).

Figure 4 illustrates the block diagram of the electronic meter

reservoir liquid level comprising:

- connector (1): path between the meter internal circuit (4) and the external peripherals (PE);

- output circuit (41): responsible for conditioning the reading signal at simulated voltage or resistance level;

- power supply (42): converts the voltage level of the battery that reaches the connector (1) to another acceptable by the internal circuit of the equipment;

- liquid level meter (43): used by the CPU (44) to determine the reservoir liquid level into which the metal profile (3) is immersed;

- central processing unit (44): collects data from all other blocks and relates them to measure the level of liquid in the reservoir; is a microcontroller (integrated circuit) with all the functions necessary to read the fuel level; temperature compensation (45): used by the CPU (44) to compensate for temperature variation; To this end, the same scheme used for reading the metal profile (3 and 5) for measuring liquid is used for measuring an internal reference component susceptible to temperature variation; when we notice increase of its effective value, we decrease the relative value of liquid, because the same electrode will be suffering this variation; if the decrease occurs, we increase the relative liquid level;

- instrument panel (7): receives the output signal from the equipment and converts it into a visual indication of the reservoir liquid level;

auxiliary electrode (6): is positioned at the base of the electronic meter and corresponds to the top of the reservoir, being responsible for detecting the presence of liquid when the reservoir is full and sending a signal to the CPU (44) that interprets the event as "full tank". "by capturing the effective value of liquid from the liquid level gauge (43) and readjusting it as the new full tank value for the system; With this new relationship, the response curve eventually adjusts to the dielectric of the liquid present in the tank; the auxiliary electrode (6) has a metal profile, being connected directly to the same external metal profile reader system (3) and being able to detect fuel by being close to the external metal profile (3), which is connected to the negative pole of Measurement - this fact makes the auxiliary electrode (6) a potential capacitor to the system, but with a lower capacitance than the external metallic profile (3).

Figure 5 illustrates the circuit of the electronic liquid level meter where the dielectric constant detection sensor of the

liquid comprising:

- channel selector (8): responsible for directing the channel to be measured between the level sensor (43), the temperature compensation (45) and the liquid dielectric constant detection sensor (6);

- oscillating circuit (9): comprising two current sources capable of releasing (91) and absorbing (92) current, are controlled by a flip-flop (93) which receives on the SET and RESET pins the signal of two comparators ( 94) controlling, by internal references (95), the maximum and minimum level of the signal generated by the current sources (91 and 92); current sources 91 and 92 are fed back by the signal generated at the flip flop output 93;

- counter (10): has as a clock the oscillation generated in the oscillator circuit (9) that when completing the edge changes generates a pulse for the next control block;

oscillator (13): is the main time source of the level meter (43) and central processing unit (44); for the level meter (43) the oscillator generates the fixed time base which is measured with respect to the oscillation generated in the block (9);

- timer (11): at each signal generated by the counter block (10) the timer captures the elapsed time since the other pulse; the time base comes from the oscillator (13); Measuring the relationship between two pulses minimizes delay or delay errors in the main control software as it puts all work on the external circuit; after capturing the time the timer (11) loads a buffer (12) with this data;

- buffer (12): location of the last time measurement taken by the circuit; This is where software looks for the value to use in its internal routines.

Figure 6 illustrates the flowchart of the meter control process.

Reservoir Liquid Level Sensor with

liquid dielectric constant comprising the following steps:

A) the battery supplies the equipment through the connector (1); After the power supply stabilization period (42), the CPU (44) is ready to begin the control process;

B) the external electrode is read (6) responsible for detecting the presence of liquid at the maximum level of the reservoir where the meter was installed;

C) Checks whether the reading value has changed from the standard ('air' reading because there is no liquid in contact with the electrode) and, if so, follows step D; otherwise, follow step E;

D) Detecting the presence of liquid in the electrode (6), the level value previously measured by the liquid level meter and related to the previous value of "tank full" in memory in the meter is captured; From this calculation, it is possible to estimate the new dielectric constant of the net by the variation found between the previous and the current data;

E) the CPU (44) activates the liquid level meter (43) which, in turn, continues to perform liquid level measurements while requested by the CPU (44);

F) the measured liquid values are buffered;

G) the CPU (44) performs repeated analyzes from the temperature compensator (45);

H) temperature compensation values are also buffered;

I) increments the reading counter, which controls the maximum number of runs of the liquid level reading algorithm and temperature compensation;

J) if the CPU (44) has received the 8 data from the liquid level meter (43) and the temperature compensator (45), it performs step K; otherwise, restart the process from step B;

K) the CPU (44) performs an average calculation with the obtained values;

L) with the averages established, the moving average of the net values read is performed;

M) In order to eliminate reading errors due to system variations caused by temperature variation (the function is necessary as liquids may undergo dielectric variations due to temperature, thus causing erroneous level measurements), the meter adjusts to perform the measurement based on ambient temperature, obtaining the effective value of liquid in the reservoir by compensating with data from the temperature compensation block (45);

N) With the effective liquid level in the reservoir, the CPU (44) rotates the data conditioning algorithm with the output circuit (41), transforming the linear reading into a predetermined curve, meeting the desired instrument panel behavior ( 7) and the geometry of the reservoir where the meter is installed; then restart the process from step B.

Claims (4)

1. "ELECTRONIC LEVEL LEVEL GAUGE DETECTOR SENSOR" which employs an external metal profile (3) with a side slit for liquid flow that acts as an external electrode in the metering system and an internal metal profile (5 ) acting as the internal electrode of the measuring system, characterized by the fact that it comprises: - two or three way connector (1); - gasket (2) which is positioned between the top cover (4) and the surface of the place where the meter will be installed; - top cover (4) housing the electronic part of the meter; - sensor for detecting the dielectric constant of the liquid supplied to the reservoir (6). 2. "ELECTRONIC LEVEL LEVEL GAUGE DETECTION SENSOR" according to Claim 1, characterized in that the electronic part of the meter comprises: - connector (1): path between the meter internal circuit (4) and external peripherals (PE); - output circuit (41): responsible for conditioning the reading signal at simulated voltage or resistance level; - power supply (42): converts the voltage level of the battery that reaches the connector (1) to another acceptable by the internal circuit of the equipment; - liquid level meter (43): used by the CPU (44) to determine the reservoir liquid level into which the metal profile (3) is immersed; - central processing unit (44): collects data from all other blocks and relates them to measure the level of liquid in the reservoir; - temperature compensation (45): used by the CPU (44) to compensate for temperature variation; - instrument panel (7): receives the output signal from the equipment and converts it into a visual indication of the reservoir liquid level; - auxiliary electrode (6) which has a metal profile, is connected directly to the external metal profile reader system (3) and is capable of detecting fuel by being close to the external metal profile (3), which is connected to the negative pole of measurement, which makes the auxiliary electrode (6) a potential capacitor to the system, but with a lower capacitance than the external metallic profile (3); the auxiliary electrode (6) sends a signal to the CPU (44) that interprets the event as a "full tank", capturing the effective liquid value from the liquid level gauge (43) and readjusting as the new full tank value to the system. 3 - "ELECTRONIC LEVEL LEVEL GAUGE DETECTION SENSOR" according to one of claims 1 or 2, characterized in that the circuit of the electronic liquid level meter comprises: - channel selector (8) ): responsible for directing the channel to be measured between the level sensor (43), the temperature compensation (45) and the liquid dielectric constant detection sensor (6); - oscillating circuit (9): comprising two current sources capable of releasing (91) and absorbing (92) current, are controlled by a flip-flop (93) which receives on the SET and RESET pins the signal of two comparators ( 94) controlling, by internal references (95), the maximum and minimum level of the signal generated by the current sources (91 and 92); current sources 91 and 92 are fed back by the signal generated at the flip flop output 93; - counter (10): has as a clock the oscillation generated in the oscillator circuit (9) that when completing the edge changes generates a pulse for the next control block; oscillator (13): is the main time source of the level meter (43) and central processing unit (44); for the level meter (43) the oscillator generates the fixed time base which is measured with respect to the oscillation generated in the block (9); - timer (11): at each signal generated by the counter block (10) the timer captures the elapsed time since the other pulse; the time base comes from the oscillator (13); Measuring the relationship between two pulses minimizes delay or delay errors in the main control software as it puts all work on the external circuit; after capturing the time the timer (11) loads a buffer (12) with this data; - buffer (12): location of the last time measurement taken by the circuit; This is where software looks for the value to use in its internal routines. 4. "ELECTRONIC LEVEL LEVEL GAUGE DETECTION SENSOR" according to one of Claims 1 to 3, characterized in that the electronic meter control process comprises the following steps: A) the battery charges the equipment through the connector (1); After the power supply stabilization period (42), the CPU (44) is ready to begin the control process; B) reading of the external electrode (6) responsible for detecting the presence of liquid at the maximum level of the reservoir where the meter was installed; C) Checks whether the reading value has been changed from the default, if yes, follows step D, if negative goes to step E; D) Detecting the presence of liquid in the electrode (6), the level value previously measured and related to the previous value of "tank full" in memory in the meter is captured; the new dielectric constant of the net being estimated by the variation found between the previous and the current data; E) the CPU (44) activates the liquid level meter (43) which, in turn, continues to perform liquid level measurements while requested by the CPU (44); F) the measured liquid values are buffered; G) the CPU (44) performs repeated analyzes from the temperature compensator (45); H) temperature compensation values are also buffered; I) increments the reading counter, which controls the maximum number of runs of the liquid level reading algorithm and temperature compensation; J) if the CPU (44) has received the data from the liquid level meter (43) and the temperature compensator (45) follow step K1 if negative restarts the process from step B; K) the CPU (44) performs an average calculation with the obtained values; L) with the averages established, the moving average of the net values read is performed; Μ) the meter adjusts to perform the measurement based on ambient temperature, obtaining the effective value of liquid in the reservoir by compensating with the temperature compensation block data (45); N) With the effective liquid level in the reservoir, the CPU (44) rotates the data conditioning algorithm with the output circuit (41), transforming the linear reading into a predetermined curve, meeting the desired instrument panel behavior ( 7) and the geometry of the reservoir where the meter is installed; then restart the process from step B.