JPH0933323A - Tank level gauge and data base constructing method for characteristic correction of liquid level detection sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple and low cost level gauge by which an accurate measurement result can be obtained based on the signal value of an electric signal in response to liquid level position regardless of the inside shape of a tank. SOLUTION: In the tank level gauge, in which the position of a displacing float 5 following the liquid level G1 of a liquid G in a tank 1 is converted into an electric signal through a potentiometer 7, and the level of the liquid G is measured based on operation processing using the signal value of the electric signal and a level operation formula, an approximate characteristic data base, which holds approximate characteristic data which are produced by approximating the output characteristic of the electric signal through the potentiometer 7 to correlation between the level of the liquid G determined corresponding to the inside shape of the tank 1 and the position of the float 5, and a signal correction means 31A, which corrects the signal value into a corrected signal value in response to an approximate characteristic held by the approximate characteristic data base, are provided so that the operation processing is conducted using the corrected signal value corrected by the signal correction means 31A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tank fuel gauge for measuring the amount of liquid remaining in a tank such as a fuel tank of a vehicle, and a liquid level detecting sensor suitable for use in the fuel gauge. The present invention relates to a method of constructing a database for correcting output characteristics.

[0002]

2. Description of the Related Art A vehicle is provided with a fuel gauge for measuring the remaining amount of gasoline, engine oil, or the like. The fuel gauge includes, for example, a sliding resistance type, an inductive type, and a hall element type. In each of these types, the float arranged in the tank is floated on the liquid surface, and the float is attached to the swing end of the float arm. The float arm follows the displacement of the liquid level to change the swing angle of the float arm, and this change changes the contact position with the base of the float arm. The resistance
Change linearly according to the swing angle of the float arm,
The potentiometer is configured to output a signal corresponding to the resistance value to, for example, a controller for driving the meter.

For example, in a fuel gauge for measuring the remaining amount of gasoline in a gasoline tank, there is a conventional Japanese Patent Laid-Open No.
As disclosed in Japanese Patent No. 4-12227, the sender output value when the tank is actually filled up is substituted into the formula for calculating the remaining gasoline amount in the tank based on the sender output of the potentiometer. In this case, there is a method in which the correction coefficient of the calculation formula is appropriately changed according to the sender output value when the tank is full so that the remaining gasoline amount corresponding to the tank is calculated.

In addition, as disclosed in Japanese Patent Laid-Open No. 63-33620, the sender output of the potentiometer is periodically sampled depending on the amount of remaining gasoline in the tank and the sampling value. In periodically calculating the remaining amount of gasoline in the tank based on, based on the previously calculated remaining amount of gasoline, determine the reference value for the sender output this time, and the selection range that is the allowable error range, There is one that appropriately corrects the present sender output value depending on whether or not the present sender output value is within the allowable error range.

Further, as disclosed in Japanese Utility Model Laid-Open No. 63-44119, an error in the sender output value caused by a change in the temperature inside the tank is corrected according to the temperature inside the tank, and the sender output is corrected. There is a method for compensating the temperature of the measured value of the remaining tank amount obtained on the basis of. All of these are aimed at accurately measuring the remaining amount in the tank.Specifically, the actual remaining amount depends on the characteristics of the potentiometer, the running condition of the vehicle in which the tank is installed, and the surrounding environment. The purpose is to eliminate the error in the output of the fuel gauge with respect to.

[0006]

As described above, various means for eliminating the error in the output of the fuel gauge relative to the actual fuel remaining amount have been proposed in the past, but in the field of fuel gauge,
In addition to this, it is necessary to provide means for accommodating the tank capacity and the internal shape that differ depending on the vehicle type and the displacement of the vehicle, and for making the output of the potentiometer match the actual remaining amount. For this purpose, the output characteristic of the potentiometer must be proportional to the magnitude of the actual remaining amount in the tank, not to the proportional movement of the float. There is a problem in that the troublesome and costly adjustment and addition of parts such as partially changing the value and partially connecting the capacitor have to be performed individually for each tank type.

In Japanese Patent Laid-Open No. 6-59558, a change in the specifications of the vehicle, for example, a current value or the like flowing in a motor coil for driving a pointer of a fuel gauge is rewritten according to a difference in tank capacity by rewriting the program. Although it is disclosed that the change is made, this is only related to the drive of the pointer, and cannot solve the above-mentioned inconvenience related to the measurement of the tank remaining amount itself.

The present invention has been made in view of the above circumstances, and a first object of the present invention is to measure the remaining amount of liquid in a tank according to the position of the float floating on the liquid surface. Based on the signal value of the electrical signal output from the liquid level detection sensor, regardless of the internal shape of the tank that influences the correlation between the amount of up and down of the liquid level and the amount of increase or decrease of the liquid, or the volume of the tank. A second object of the present invention is to provide a simple and inexpensive fuel gauge capable of obtaining accurate measurement results, and a second object of the present invention is to use a liquid level detection sensor suitable for this fuel gauge. It is to provide a method of constructing a database for correcting the output characteristics of.

[0009]

In order to achieve the first object, the tank fuel gauge of the present invention has a liquid level G1 of a liquid G in a tank 1 as shown in the basic configuration diagram of FIG. A tank that converts the position of the float 5 that is displaced following it into an electric signal by the potentiometer 7 and measures the remaining amount of the liquid G based on the calculation process using the signal value of this electric signal and the remaining amount calculation formula. In the internal fuel gauge, the output characteristic of the electric signal by the potentiometer 7 is approximated to a correlation between the residual amount of the liquid G and the position of the float 5 which is determined according to the internal shape of the tank 1. An approximate characteristic database 33 that holds data, and a signal value correcting unit 31A that corrects the signal value into a correction signal value according to the approximate characteristic that the approximate characteristic database 33 holds, are provided. Using the correction signal value corrected by the stage 31A is characterized in that to perform the calculation processing.

Further, according to the present invention, the approximate characteristic database 33 holds a corrected remaining amount calculation formula obtained by correcting the remaining amount calculation formula according to the approximate characteristic as the data, and the signal value correction means 31A, In the process of the arithmetic processing, the signal value is corrected to the correction signal value.

Further, in order to achieve the second object, the method for constructing the database for correcting the characteristic of the liquid surface detecting sensor of the present invention outputs an electric signal having a signal value corresponding to the position of the liquid surface of the liquid in the tank. A method for constructing a characteristic correction database for correcting the output characteristic of the electric signal of the liquid level detection sensor to a characteristic according to the internal shape of the tank, wherein the remaining amount of the liquid in the tank is known. The state in which the tank is empty, link data linking the remaining amount of the liquid in the above state and the signal value of the electric signal output by the liquid level detection sensor corresponding to the remaining amount, A state in which the tank is full and a state in which the remaining amount of the liquid is at least one remaining amount other than the empty and full tanks are acquired in advance, and the signal values of the link data are adjacent to each other. Two Based on the link data, a plurality of remaining amount calculation formulas for calculating the remaining amount of the liquid are calculated from the signal values between these two adjacent signal values, and the respective remaining amount calculation formulas are used to calculate the respective remaining amount calculations. It is characterized in that data of adjacent signal values of the two link data based on which the equation is calculated is managed as an address so as to be searchable.

According to the present invention, the link data is obtained by storing a known amount of the liquid in the tank and measuring the signal value of the electric signal output by the liquid level detection sensor in this state. I decided to do it.

According to the tank fuel gauge of the present invention, the potentiometer 7 is operated by the signal value correcting means 31A based on the data of the approximate characteristics held in the approximate characteristic database 33.
The signal value of the electric signal output by the liquid G is corrected not to be proportional to the ascending / descending amount of the float 5 but to the correction signal value on the approximate characteristic proportional to the increase / decrease amount of the liquid G in the tank 1. The tank 1 having a complicated internal shape in which the increase / decrease amount and the ascending / descending amount of the liquid level G1 are not necessarily proportional, or the increasing / decreasing amount of the liquid G and the ascending / descending amount of the liquid level G1 are proportional, but depending on the type, Various tanks 1 such as tanks 1 with different capacities
Both of the above can be widely supported by a single-structure fuel gauge.

Further, the approximate characteristic database 33 is
The correction remaining amount calculation formula obtained by correcting the remaining amount calculation formula according to the approximate characteristic is held as the data, and the signal value correction means 31A corrects the signal value to the correction signal value in the process of the arithmetic processing. With such a configuration, the correction processing of the signal value to the correction signal value performed by the signal value correction means 31A can be simultaneously performed in the arithmetic processing, and the correction processing by the signal value correction means 31A is performed. Since it is not necessary to perform the calculation processing independently from the calculation processing, the remaining amount measurement can be speeded up accordingly.

Further, according to the method for constructing the database for correcting the characteristic of the liquid level detecting sensor of the present invention, the known remaining amount of the liquid in the tank and the liquid level detecting sensor corresponding to the remaining amount by the link data. Correlation with the signal value of the electric signal output by is obtained only for each section (range of signal value) that divides the tank from the empty state to the full state,
During actual operation of measuring the remaining amount of liquid in the tank, calculate the remaining amount of liquid in the tank from the signal value during actual measurement using the signal value of the electric signal output by the liquid level detection sensor as an address pointer. A remaining amount calculation formula suitable for this is retrieved from a plurality of remaining amount calculation formulas and output.

Therefore, when measuring the amount of liquid remaining in the tank, the tank has a complicated internal shape such that the amount of increase and decrease of the liquid and the amount of elevation of the liquid surface are not necessarily proportional, or Is proportional to the amount of increase / decrease of the liquid and the amount of rise / fall of the liquid level, but even if the capacity when the tank is full varies depending on the type, the actual tank It is possible to obtain a highly accurate remaining amount that is close to the remaining amount by calculation.

The link data can be obtained, for example, by storing a known amount of liquid in the tank and actually measuring the signal value of the electric signal output by the liquid level detection sensor in this state.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION A method of constructing a database for correcting the output characteristic of a liquid surface detecting sensor according to the present invention will be described below with reference to a fuel gauge based on the drawings. FIG. 2 is an explanatory diagram showing a schematic block diagram of a fuel gauge according to an embodiment of the present invention in a partial block, in which 1 is a gasoline tank and 3 is a fuel gauge.

The gasoline tank 1 is connected via a pipe 15 to an oil supply port 11 which is opened and closed by a cap 13 on the rear side of a vehicle (not shown), and is supplied with oil from a fueling nozzle N at a gas station or the like. The gasoline G poured into the mouth 11 is configured to be stored inside. In the figure, the gasoline tank 1 is schematically shown in a small scale with respect to the pipe 15 and the like. The gasoline tank 1 is provided with a float 5 and a potentiometer 7 for measuring the amount of gasoline remaining inside.

The float 5 is made of a material that is highly resistant to the erosion by the gasoline G, and is made of a liquid level G of the gasoline G.
It has a relatively light weight so that it can float on 1. The potentiometer 7 includes a float arm 71 that supports the float 5 so that the float 5 can swing, and the float arm 7
1. A support shaft 73 that supports 1 for swinging, a swing arm 75 that is connected to the float arm 71 via the support shaft 73 and swings integrally with the float arm 71. Is connected to a grounded sender resistor Rx. In the potentiometer 7, the float 5 moves up and down following the liquid level G1 of the gasoline G, and the float arm 71 and the swing arm 75 swing integrally with the float 5, so that the tip of the swing arm 75 slides. The moving contact 75a slides on the sender resistance Rx, and the resistance value rx of the sender resistance Rx changes according to the sliding position of the sliding contact 75 depending on the liquid level G1 position of the gasoline G in the gasoline tank 1. Is configured.

Although the potentiometer 7 arranged outside the gasoline tank 1 is shown in the drawing, the potentiometer 7 may be arranged inside or outside the gasoline tank 1. Further, in the drawings, the swing arm 75, its sliding contact 75a, and the center resistance Rx are each symbolized for easy understanding of the drawing. And
In the present embodiment, the float 5 and the potentiometer 7 constitute a liquid level detection sensor.

The fuel gauge 3 includes the potentiometer 7
Input terminal Ia to which the spindle 73 of the above is connected, a microcomputer (CPU) 31 connected to this input terminal Ia, a non-volatile memory (NVM) 33 and a driver 35a connected to this microcomputer 31, and this driver 35a. And a fuel gauge 35 for displaying the remaining amount of gasoline in the gasoline tank 1 driven by the input terminal Ia and the CPU 3
The signal line L connecting 1 is pulled up by the pull-up power supply Vb and the pull-up resistor Rb inside the fuel gauge 3. Further, the fuel gauge 3 includes an auxiliary input terminal Ib for fetching data to be written in a database built in the NVM 33, and a CPU 31 and an external device of the fuel gauge 3 via the auxiliary input terminal Ib. An interface (I / F) 37 for adjusting the communication format of data transmitted between the devices is further provided.

The CPU 31 digitally converts the sender output S generated on the signal line L when the potentiometer 7 is connected to the input terminal Ia of the A / D converter 31a.
And a RAM 31b and a ROM 31c. The RAM 31b is provided with a data area for storing data read from the database of the NVM 33 and a work area used for various kinds of processing work.
The OM 31c stores a control program for causing the CPU 31 to perform various processing operations.

The data to be written in the database built in the NVM 33 is input from the tester 9 connected to the auxiliary input terminal Ib in this embodiment.
The tester 9 connects the ground side terminal of the sender resistor Rx and the support shaft 73 to a tester rod or the like as shown by the broken line in FIG. 2 so that the sender resistor Rx corresponding to the sliding position of the sliding contact 75a. Resistance value rx is measured and displayed, and a conventionally known tester function necessary for that purpose is provided. In addition to this, the tester 9 links the measured resistance value rx with the value of the amount of gasoline G in the gasoline tank 1 to be described later, and temporarily stores link data including the value of the amount of gasoline G and the resistance value rx. A buffer (not shown) having a capacity for a plurality of sets of link data, which is necessary for that.
It has. Further, the tester 9 sends a plurality of link data in the buffer to the CPU via the auxiliary input terminal Ib.
Further, a microcomputer (not shown) for sending the link data to the CPU 31 in the communication format corresponding to the I / F 37 when sending the data to the CPU 31 is further provided.

The tester 9 measures the resistance value rx of the sender resistance Rx connected by a tester rod or the like in a state where a known amount of gasoline G is stored in the gasoline tank 1.
For example, the resistance value rx is displayed on a display unit (not shown), and the link data in which the known amount of gasoline G at that time and the resistance value rx are linked are stored in a buffer and stored in this buffer. When the tester 9 is connected to the auxiliary input terminal Ib, the CPU 31
It is configured to output in response to a request from.

In the buffer, at least the link data in which the gasoline G in the gasoline tank 1 is zero, the link data in the full tank (70 liters in the present embodiment), and some types in between. A plurality of sets of link data with the link data in a state where the amount of gasoline G is stored in the gasoline tank 1 are stored and accumulated until there is a request from the CPU 31. The known amount of gasoline G in the gasoline tank 1 in each state stored in the buffer as a part of the link data may be recorded in the internal memory of the tester 9 in advance, or The tester 9 is provided with input setting means (not shown) such as a numeric keypad,
The input value may be set by the input setting means when the resistance value rx of the sender resistor Rx is stored in the buffer.

When the known amount of gasoline G is recorded in the internal memory of the tester 9 in advance,
For example, the known amount of gasoline G from the internal memory is 1
Each of them is read out one by one (for example, from the state of zero gasoline G) and displayed on the display unit (not shown) or the like, and the known amount of gasoline G is stored in the gasoline tank 1 while observing the display, and in this state, The measured resistance value rx of the sender resistance Rx is linked with the known amount of gasoline G read from the internal memory and stored in the buffer as link data. When inputting and setting the known amount of gasoline G from an input setting means such as a numeric keypad, a known amount of gasoline G is stored in the gasoline tank 1 and the known amount of gasoline G is input from the input setting means. The input resistance is set, and in that state, the measured resistance value rx of the sender resistance Rx is linked to the known input gasoline quantity of the gasoline G and stored in the buffer as link data.

The broken line connecting the tester 9 and the auxiliary input terminal Ib in the figure shows the CPU 31 via the tester 9 as the data to write the link data stored in the buffer of the tester 9 into the database built in the NVM 33. It is shown that the connection is selectively made only when it is taken in. At this time, the connection between the support shaft 73 and the input terminal Ia is disconnected.

Next, the processing performed by the CPU 31 in accordance with the program stored in the ROM 31c will be described with reference to the flow charts of FIGS. When the program of the ROM 31c is started, the CPU 31 confirms whether or not the auxiliary input terminal Ib is open (step S1) as shown in the general flowchart of FIG. 3, and if it is open (Y in step S1). , Step S5
If not open (N in step S1),
After performing the tank shape database creation process (step S3), the process proceeds to step S5.

In step S5, it is confirmed whether or not the ignition switch (IGN) of the vehicle (not shown) is on. If it is not on (N in step S5), the process returns to step S1 and is on. If (Step S
5), it is checked whether the input terminal Ia is open (step S7). If the input terminal Ia is open (Y in step S7), the process returns to step S1. If it is not open (N in step S7), after the gasoline remaining amount measurement display process is performed (step S9), step S1 is performed. Return to.

In the tank shape database creation processing of step S3, as shown in the flowchart of the subroutine of FIG. 4, a plurality of link data from the tester 9 input from the auxiliary input terminal Ib are read (step S3).
01), based on the read plurality of link data, a reference table for selection of a calculation formula used for measuring the remaining amount of gasoline G in the gasoline tank 1 is created (step S30).
3). As shown in FIG. 6, in the comparison table, the gasoline level in the gasoline tank 1 is based on the resistance value rx converted from the sender output S by the CPU 31 in the gasoline remaining amount measurement display process of step S9 described in detail later. When measuring the remaining amount of G, the remaining amount calculation formula of the plurality of gasoline G selected according to the magnitude of the resistance value rx, and the remaining amount calculation formula of the plurality of gasoline G according to the resistance value rx In this example, the range of the resistance value rx, which is an application criterion of the remaining amount calculation formula of each gasoline G, is used in a one-to-one correspondence.

The formula for calculating the remaining amount of each gasoline G is as follows.
It is decided like. That is, for example, the tester 9
The number of link data read from is 6
The contents of the six link data are the gas in the gasoline tank 1.
Volume data of Sorin G [0 liter, 10 liter, 1
7.5 liters, 35 liters, 52.5 liters, 7
Each value of 0 liter (full tank)] and amount of each gasoline G
The resistance value r of the sender resistance Rx measured by the tester 9 at
x (re, r_Ten, R_17.5, R₃₅, R _52.5, R₇₀) Is
In this case, the calculation formula is such that the resistance value rx is re ≦ rx <r.
_TenRange of r_Ten≤rx <r_17.5Range of r_17.5≤rx <
r₃₅Range of r₃₅≤rx <r _52.5Range and R
_52.5≤rx <R₇₀5 types to be applied for each range
Becomes Then, each calculation formula uses the range of the resistance value rx as ra.
When ≦ rx <rb, the remaining amount M of gasoline G =
{(B−a) · (rx−ra) / (rb−ra)} + a
Can be represented by the general formula Control of step S303
Once the table has been created, set the reference table to N
After storing in the VM 33 (step S305), the main routine
Return to Chin. In the present embodiment, this comparison table
Is stored in the NVM 33.
It is equivalent to the database.

In the gasoline remaining amount measurement / display process of step S9, as shown in the flowchart of the subroutine of FIG. 5, the sender output S input via the input terminal Ia and the signal line L is transferred to the A / D converter 31a. Digital conversion is performed (step S901), and the sender output S after the digital conversion is converted into the resistance value rx in the calculation area based on the voltage value of the pull-up power supply Vb and the resistance value of the pull-up resistor Rb ( Step S903).

Then, the converted resistance value rx is used as an address pointer to search the comparison table, and re ≦ rx
<Range of r _10, the range of _{r 10 ≦ rx <r 17.5,} r 17.5 ≦ r
x <r ₃₅ range, r ₃₅ ≦ rx <r _52.5 range, and
It is determined which range of formulas R _52.5 ≤rx <R ₇₀ is applied (step S905), and the determined formula is applied to calculate the remaining amount M of the gasoline G in the gasoline tank 1. (Step S907), and the calculated remaining amount M
After driving the gauge 35 by the driver 35a so as to instruct (step S909), the process returns to the main routine. As is clear from the above description,
In the present embodiment, the signal value correction means 31A in the claims is constituted by step S907 in the flowchart of FIG.

Next, the operation (action) of the fuel gauge 3 of the present embodiment configured as described above will be described. Fuel gauge 3
When assembling into the vehicle, the support shaft 73 of the potentiometer 7 attached to the gasoline tank 1 of the vehicle,
Before connecting to the input terminal Ia of the fuel gauge 3, connect to the plus side tester rod of the tester 9, and connect the minus side tester rod to
Connect to the ground side terminal of the sender resistor Rx. Then, the amount of gasoline G in the gasoline tank 1 is set to 0 liter, 10
Liter, 17.5 liter, 35 liter, 52.5
The resistance value rx of the sender resistance Rx corresponding to the position of the float 5 in each state is measured with the tester 9 to obtain each measurement resistance value rx.
Six pieces of link data in which the amount of gasoline G in the gasoline tank 1 corresponding thereto is linked are stored in the buffer of the tester 9.

Next, the plus and minus tester rods are used as the support shaft 7.
3 and the sender resistor Rx from the ground terminal,
The tester 9 is connected to the auxiliary input terminal Ib of the fuel gauge 3. Then, in response to a request from the CPU 31 that detects that the auxiliary input terminal Ib is in the closed state, the six pieces of link data stored in the buffer are sent to the CPU via the I / F 37.
31 is read, and from the 6 link data, FIG.
A comparison table composed of the five calculation formulas shown in 3 and the applicable resistance value range is created and stored in the NVM 33. At this time, when the contrast table is already stored in the NVM 33, the old contrast table is erased and the new contrast table is stored.

When the above work is completed, the spindle 73 of the potentiometer 7 is connected to the input terminal Ia of the fuel gauge 3,
The assembling of the fuel gauge 3 to the vehicle is completed. After that, IG
With the N switch on, the sender output S digitally converted by the A / D converter 31a of the CPU 31
From the sender resistance R that changes according to the position of the float 5 that follows the liquid level G1 of the gasoline G in the gasoline tank 1.
The resistance value rx of x is converted, the remaining amount M of the gasoline G is calculated by applying the calculation formula selected according to the resistance value rx, and the remaining amount M is instructed by the gauge 35.

The remaining amount M of gasoline G indicated by the gauge 35 is in the link data read from the tester 9, and the value is 0 liter, 10 liter, 17.5 liter actually measured by the tester 9. , 35 liters, 52.5 liters, and 70 liters, the calculated value has no error. Further, for the remaining amount M other than the above-described six remaining amounts, the indicated point of the gauge 35 is determined by the calculation formula determined based on the remaining amount M actually measured by the tester 9 before and after the remaining amount M. The characteristics between the two resistance values rx of the sender resistance Rx corresponding to the remaining amount M actually measured by the tester 9 before and after that, that is, the characteristics shown by the solid line in FIG.
An approximate characteristic in which the two resistance values rx are connected by a straight line, that is,
The characteristic is indicated by the broken line in FIG. 7, and the remaining amount M on the gauge 35 calculated on the replaced approximate characteristic is designated.

As described above, according to this embodiment, the sender resistance R of the potentiometer 7 depends on the position of the float 5 floated on the liquid level G1 of the gasoline G in the gasoline tank 1.
The resistance value rx of x is changed, the data of this resistance value rx is fetched into the CPU 31, and the gasoline tank 1
In the fuel gauge 3 for measuring the remaining amount of gasoline G in the inside, a NVM 33 is provided as a database for storing the data of the characteristics of the sender resistance Rx that changes according to the internal shape and capacity of the gasoline tank 1 as tank shape data. It was configured.

Before the use of the fuel gauge 3, the state in which the inside of the gasoline tank 1 to be measured is emptied and the gasoline G whose amount has been measured in advance are put in the gasoline tank 1 and the gasoline tank 1 In the state where the amount of gasoline G inside is 10 liters, 17.5 liters, 35 liters, 52.5 liters, and 70 liters, respectively, the resistance values re and r _{10 of} the sender resistance Rx measured by the tester 9 are measured. , R _17.5 , r ₃₅ , r _52.5 , r ₇₀ in the form of link data in which the amount of gasoline G corresponding to each resistance value re, r ₁₀ , r _17.5 , r ₃₅ , r _52.5 , r ₇₀ is linked, The CPU 31 can be loaded from the tester 9.

Further, according to this embodiment, when the CPU 31 calculates the remaining amount M of the gasoline G from the resistance value rx of the sender resistance Rx when the fuel gauge 3 is used, based on the link data taken from the tester 9. The resistance value rx measured by the tester 9 is the resistance value re, r ₁₀ , r
Create 5 types to use properly depending on which of the two resistance values among _17.5 , r ₃₅ , r _52.5 and r ₇₀ belong, and calculate the 5 types of calculation formulas and what value the resistance value rx is. Data having a set of a range of the resistance value rx indicating whether to use the formula is stored in the NVM 33 as the tank shape data.

Therefore, simply, the resistance value re of the sender resistance Rx when the gasoline tank 1 is empty and the sender resistance Rx when the amount of gasoline G in the gasoline tank 1 is 70 liters (full tank). Compared with the case where the CPU 31 calculates the remaining amount M of the gasoline G in the gasoline home 1 based on the resistance value rx of the sender resistance Rx converted from the sender output S according to the characteristic that is linearly connected to the resistance value r _{70 of} , The difference between the measured remaining amount M and the actual remaining amount is reduced, and the measurement accuracy is significantly improved. As a result, the value indicated by the gauge 35 can be made as close as possible to the actual remaining amount M of the gasoline G. it can. That is, it is possible to realize a highly reliable fuel gauge 3 that conforms to the internal shape and capacity of the gasoline tank 1.

Of the link data acquired in advance, the number of link data in the state where the remaining amount of the liquid G in the tank 1 is set to the remaining amount other than empty and full is 4 data ( Amount of gasoline G = 10 liters,
It is not limited to each data of 17.5 liters, 35 liters, and 52.5 liters), and it is optional as long as it is 1 data or more, and the numerical value of the known amount of gasoline is also arbitrary. And, as a matter of course, as the number of link data increases, the number of formulas for calculating the remaining amount of gasoline also increases, and the range of values for replacing the actual sender resistance characteristic with the approximate linearity characteristic becomes narrower. The error of the approximate characteristic to the actual characteristic is smaller, which further improves the accuracy of the calculated gasoline remaining amount in the tank, and the remaining of various gasoline tanks with complicated internal shapes and slight capacity differences. As a quantity meter, it is possible to flexibly respond with a single configuration.

Further, the link data may be obtained by calculation, for example, based on CAD data including numerical data such as dimensions capable of specifying the internal shape and capacity of the gasoline tank. Furthermore, the present invention is not limited to a gasoline tank, and is mounted on a vehicle to store liquid, for example, a radiator or an engine oil tank, a window washer tank, a power steering oil tank, or the like, or a water tank used outside the vehicle, Needless to say, it can be widely applied to various fuel gauges for measuring the amount of liquid remaining in tanks such as fuel tanks for combustors such as kerosene and heavy oil.

[0045]

As described above, according to the tank fuel gauge of the present invention, the position of the float, which is displaced following the liquid level of the liquid in the tank, is converted into an electric signal by the potentiometer, and this electric signal is converted. Based on the calculation process using the signal value and the remaining amount calculation formula, in the tank fuel gauge for measuring the remaining amount of the liquid, the output characteristic of the electric signal by the potentiometer, the internal shape of the tank According to the approximate characteristic database that holds the data of the approximate characteristic that is approximated to the correlation between the remaining amount of the liquid and the position of the float that is determined in accordance with the approximate characteristic that the signal value is held by the approximate characteristic database. A signal value correcting means for correcting the signal value is provided, and the arithmetic processing is performed using the corrected signal value corrected by the signal value correcting means.

Therefore, the signal value of the electric signal output from the potentiometer is calculated by the signal value correcting means based on the data of the approximate characteristic held in the approximate characteristic database.
The signal is corrected to a correction signal value on the approximate characteristic that is not proportional to the float up / down amount, but is proportional to the liquid increase / decrease amount in the tank. It is possible to obtain an accurate measurement result based on the signal value of the electric signal output from the liquid level detection sensor, regardless of the internal shape of the tank that affects the tank capacity or the tank capacity.

Further, according to the method for constructing the database for correcting the characteristic of the liquid level detecting sensor of the present invention, the electric power of the liquid level detecting sensor for outputting the electric signal having the signal value corresponding to the position of the liquid level of the liquid in the tank A method of constructing a database for characteristic correction for correcting the output characteristics of a signal to a characteristic according to the internal shape of the tank, wherein the remaining amount of the liquid in the tank is known when the remaining amount of the liquid is known. Link data in which the amount and the signal value of the electric signal output by the liquid level detection sensor are linked to each other in accordance with the remaining amount are linked to each other. And a state in which the remaining amount of the liquid is set to at least one remaining amount other than the empty and full tanks, and based on two link data in which the signal values are adjacent to each other among the link data. , This A plurality of remaining amount calculation formulas for calculating the remaining amount of the liquid from signal values between two adjacent signal values, and each of the remaining amount calculation formulas is used as a basis for calculating each of the remaining amount calculation formulas. Data of adjacent signal values of the two link data are managed as addresses so that they can be searched.

Therefore, when measuring the amount of liquid remaining in the tank, the tank has a complicated internal shape such that the amount of increase / decrease of the liquid and the amount of elevation of the liquid surface are not necessarily proportional, Alternatively, although the increase / decrease amount of the liquid and the ascending / descending amount of the liquid level are proportional, even if the capacity when full is different depending on the type, the actual It becomes possible to obtain a highly accurate remaining amount that is close to the remaining amount in the tank by calculation, and there is an effect that it is suitable for use in the in-tank remaining amount gauge of the present invention.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of a tank fuel gauge according to the present invention.

FIG. 2 is an explanatory view showing a schematic block diagram of a fuel gauge according to an embodiment of the present invention.

FIG. 3 is a general flowchart showing a process performed by a CPU in FIG. 2 according to a program stored in a ROM.

FIG. 4 is a flowchart showing a subroutine of the tank shape database creation processing of FIG.

FIG. 5 is a flowchart showing a subroutine of a gasoline remaining amount measurement display process of FIG. 3;

6 is an explanatory diagram of a calculation formula selection reference table created in the tank shape database creation process of FIG. 4;

FIG. 7 is a correlation diagram between the actual characteristics of the sender resistance shown in FIG. 2 and the approximate characteristics replaced with the actual characteristics.

[Explanation of symbols]

 1 Tank 3 Fuel Gauge 31 CPU 31A Signal Value Correction Means 33 Approximate Characteristic Database 5 Float (Liquid Level Detection Sensor) 7 Potentiometer (Liquid Level Detection Sensor) G Liquid G1 Liquid Liquid Level

Claims (4)

[Claims] 1. A position of a float, which is displaced following the liquid surface of a liquid in a tank, is converted into an electric signal by a potentiometer, and based on a calculation process using a signal value of this electric signal and a remaining amount calculation formula. In the tank fuel gauge for measuring the remaining amount of the liquid, the output characteristic of the electric signal by the potentiometer, in the correlation between the remaining amount of the liquid and the position of the float determined according to the internal shape of the tank. An approximation characteristic database that holds data of approximated approximation characteristics, and a signal value correction unit that corrects the signal value to a correction signal value according to the approximation characteristics that the approximation characteristic database holds, the signal value correction The tank fuel gauge, wherein the arithmetic processing is performed using the correction signal value corrected by the means. 2. The approximate characteristic database holds, as the data, a correction residual amount calculation formula obtained by correcting the residual amount calculation formula according to the approximate characteristic, and the signal value correction means in the process of the arithmetic processing. The tank fuel gauge according to claim 1, wherein the signal value is corrected to the correction signal value. 3. The output characteristic of the electric signal of the liquid level detection sensor that outputs an electric signal having a signal value corresponding to the position of the liquid level of the liquid in the tank is corrected to a characteristic according to the internal shape of the tank. Is a method for constructing a characteristic correction database, in which the remaining amount of the liquid in a state where the remaining amount of the liquid in the tank is known, and the liquid level detection sensor outputs corresponding to the remaining amount. Link data in which the signal value of the electric signal is linked to the tank is empty, the tank is full, and the remaining amount of the liquid is at least one other than empty and full. The state of the remaining amount is acquired in advance, and based on two link data in which the signal values of the respective link data are adjacent to each other, based on the signal values between these two adjacent signal values, the remaining amount of the liquid is determined. To calculate the amount A plurality of remaining amount calculation formulas, and each of the remaining amount calculation formulas is managed so that the data of adjacent signal values of the two link data based on the calculation of the respective remaining amount calculation formulas can be searched as an address. A method for constructing a database for correcting the characteristics of a liquid surface detection sensor, characterized by the above. 4. The link data is acquired by accumulating a known amount of the liquid in the tank and measuring the signal value of the electric signal output by the liquid level detection sensor in this state. A method for constructing a database for correcting the characteristics of the liquid surface detection sensor according to claim 3.