JP3273459B2 - Database construction method for characteristic correction of tank fuel gauge and liquid level detection sensor - Google Patents

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 the fuel tank of a vehicle, and a liquid level detecting sensor suitable for the fuel gauge. The present invention relates to a method for constructing an output characteristic correction database.

[0002]

2. Description of the Related Art A vehicle is provided with a fuel gauge for measuring the remaining amount of gasoline, engine oil and the like. This fuel gauge includes, for example, a sliding resistance type, an induction type, a Hall element type, and the like. In each case, a float provided in a tank floats on a liquid surface, and the float is moved to a swing end of a float arm. The swingable angle of the float arm is changed by following the float to the displacement of the liquid surface, and the change in the contact position with the base of the float arm is changed by this change. The resistance value
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 control device for driving the meter.

[0003] For example, some fuel gauges for measuring the gasoline remaining quantity in a gasoline tank have been disclosed in Japanese Unexamined Patent Publication No.
As disclosed in Japanese Patent Application Laid-Open No. 4-1227, a sender output value when the tank is actually full is substituted into a calculation formula for calculating the gasoline remaining amount in the tank based on the sender output of the potentiometer. In some cases, the correction coefficient in the above formula is appropriately changed according to the sender output value when the tank is full so that the gasoline remaining amount corresponding to the full tank is also calculated.

In addition, as disclosed in JP-A-63-33620, the sender output of the potentiometer is periodically sampled when the amount of gasoline remaining in the tank is large and small. In calculating the gasoline remaining amount in the tank periodically based on the above, based on the previously calculated gasoline remaining amount, a reference value for the current sender output and a selection range that is an allowable error range thereof are determined, In some cases, the current sender output value is appropriately corrected depending on whether or not the current sender output value falls within the allowable error range.

Further, as disclosed in Japanese Utility Model Application Laid-Open No. 63-44119, an error in a sender output value caused by a change in the tank temperature is corrected in accordance with the tank temperature, and the sender output value is corrected. There is a method of compensating for the measured value of the remaining amount of the tank obtained based on the temperature. These are all 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 mounted, and the surrounding environment. The purpose of the present invention is to eliminate the error of the output of the fuel gauge with respect to.

[0006]

As described above, various means for eliminating the error of the output of the fuel gauge with respect to the actual remaining quantity have been proposed in the past, but in the field of fuel gauges,
In addition to this, a means is required to cope with the tank capacity and the internal shape that differ depending on the type and displacement of the vehicle, and to match the output of the potentiometer with the actual remaining amount. For this purpose, the output characteristic of the potentiometer must be not proportional to the amount of rise and fall of the float, but must be proportional to the amount of the actual remaining amount in the tank. There has been a problem in that troublesome and costly adjustment and addition of parts, such as partially changing values and partially connecting capacitors, must be performed with individual contents for each type of tank.

Japanese Unexamined Patent Publication No. 6-55958 discloses a program for rewriting a current value and the like flowing through a motor coil for driving a pointer of a fuel gauge in accordance with a change in vehicle specifications, for example, a difference in tank capacity. Although a change is disclosed, this only relates to driving of the hands, and cannot solve the above-mentioned problem relating to the measurement of the remaining amount of the tank 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 amount of liquid remaining in a tank in accordance with the position of a float floating on the liquid surface. Depends on the correlation between the rise and fall of the liquid level and the amount of increase and decrease of the liquid, or on the basis of the signal value of the electric signal output from the liquid level detection sensor irrespective of the internal shape of the tank which affects the capacity of the tank It is another object of the present invention to provide a simple and inexpensive fuel gauge capable of obtaining an accurate measurement result, and a liquid level detection sensor suitable for use in the fuel gauge. The object of the present invention is to provide a method for constructing an output characteristic correction database.

[0009]

In order to achieve the first object, a fuel gauge in a tank according to the present invention follows a liquid level of a liquid G in a tank 1 as shown in a basic configuration diagram of FIG. The position of the float 5 that is displaced is converted into an electric signal by the potentiometer 7 and the remaining amount in the tank for measuring the remaining amount of the liquid is calculated based on a signal value of the electric signal and a calculation process using a remaining amount calculation formula. In the meter, the output characteristic of the electric signal by the potentiometer 7 holds data of approximate characteristics in which the output characteristic of the electric signal is approximated to the correlation between the remaining amount of the liquid determined according to the internal shape of the tank 1 and the position of the float 5. Approximate characteristic database 33 and the approximate characteristic database 3
A selection target table holding a calculation formula used for measuring the remaining amount of liquid in the tank 1 based on the data held in the storage unit 3, and a signal of an electric signal output from the potentiometer 7.
The value is compared with the amount of increase or decrease of the liquid in the tank 1 according to the data of the approximate characteristics held in the approximate characteristic database.
And a signal value correcting means 13A for correcting the correction signal on the approximation characteristic for example, and compares the corrected correction signal and said selection object table by the signal value correction unit 13A, data approximate to the correction signal Before calculating the liquid remaining amount calculation formula corresponding to
Searching from serial selection object table, characterized in that the liquid remaining in the tank 1 was so that to computation.

Further, the present invention is pre-SL signal value correcting means,
In the course 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 a database for correcting characteristics of a liquid level detection sensor according to the present invention outputs an electric signal having a signal value corresponding to the position of the liquid level in the tank. A method for constructing a characteristic correction database for correcting an output characteristic of the electric signal of a liquid level detection sensor to a characteristic according to an internal shape of the tank, wherein the remaining amount of the liquid in the tank is known. Link data linking the remaining amount of the liquid in the liquid state and the signal value of the electric signal output by the liquid level detection sensor in accordance with the remaining amount, the state in which the tank is empty, 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 state and the full state 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 calculating formulas for calculating the remaining amount of the liquid from the signal values between these two adjacent signal values are calculated, and each of the remaining amount calculating formulas is calculated. The present invention is characterized in that data of adjacent signal values of the two link data based on which the formula is calculated are managed so as to be searchable as an address.

Further, according to the present invention, the link data is obtained by storing a known amount of the liquid in the tank and actually measuring the signal value of the electric signal output by the liquid level detection sensor in this state. To do.

According to the in-tank fuel gauge of the present invention, the potentiometer 7 is controlled by the signal value correcting means 31A based on the approximate characteristic data held in the approximate characteristic database 33.
Is corrected not to be proportional to the amount of rise and fall of the float 5 but to a correction signal value on an approximate characteristic proportional to the amount of increase and decrease of the liquid G in the tank 1. The tank 1 has a complicated internal shape in which the increase / decrease amount is not necessarily proportional to the rise / fall amount of the liquid surface G1, or the increase / decrease amount of the liquid G and the rise / fall amount of the liquid surface G1 are proportional to each other. Various tanks 1 such as tanks 1 with different capacities
In any case, a single fuel gauge can be widely used.

The approximate characteristic database 33 is
A correction remaining amount calculation formula obtained by correcting the remaining amount calculation formula according to the approximation characteristic is held as the data, and the signal value correction unit 31A corrects the signal value to the correction signal value in the process of the arithmetic processing. With this configuration, the signal value correcting means 31A can simultaneously perform the correction processing of the signal value to the corrected signal value in the arithmetic processing, and the correction processing by the signal value correcting means 31A It is not necessary to perform the calculation process separately and independently, and the measurement of the remaining amount can be accelerated accordingly.

Further, according to the method of constructing the database for correcting characteristics of the liquid level detection sensor according to the present invention, the remaining amount of the liquid in the tank known by the link data and the liquid level detection sensor corresponding to the remaining amount are known. The correlation with the signal value of the electric signal output by is obtained for each section (range of signal values) that divides the tank from an empty state to a full state into several sections,
During operation in which the remaining amount of liquid in the tank is actually measured, the signal value of the electric signal output by the liquid level detection sensor is used as an address pointer to calculate the remaining amount of liquid in the tank from the signal value being measured. A formula for calculating the remaining amount suitable for performing the search is retrieved and output from the plurality of remaining formulas.

Therefore, when measuring the remaining amount of liquid remaining in the tank, the tank has a complicated internal shape in which the amount of increase and decrease of the liquid is not necessarily proportional to the amount of rise and fall of the liquid level. Although the amount of increase and decrease of the liquid and the amount of rise and fall of the liquid level are proportional to each other, even if the capacity when the tank is full differs depending on the type, the actual tank based on the output of the single level liquid level detection sensor is used. It is possible to obtain a highly accurate remaining amount approximate to the inner 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]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for constructing a database for correcting output characteristics of a liquid level detection sensor according to the present invention will be described below with reference to the drawings together with a fuel gauge. FIG. 2 is an explanatory view showing a schematic configuration of a fuel gauge according to an embodiment of the present invention in a partial block, wherein 1 is a gasoline tank, and 3 is a fuel gauge.

The gasoline tank 1 is connected via a pipe 15 to a refueling port 11 which is opened and closed by, for example, a cap 13 on a rear side of a vehicle (not shown). It is configured so that gasoline G poured into the mouth 11 accumulates inside. In the drawing, the gasoline tank 1 is schematically shown on 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 remaining gasoline inside.

The float 5 is made of a material having high resistance to erosion by gasoline G, and
It is formed to be relatively lightweight so that it can float on one. The potentiometer 7 includes a float arm 71 for swingably supporting the float 5 and a float arm 7.
1, a swing arm 75 connected to the float arm 71 through the support shaft 73 and swinging integrally with the float arm 71, and one end made of, for example, a winding resistor. And a grounded sender resistor Rx. The potentiometer 7 is configured such that 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 together as a result, whereby 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 according to the liquid level G1 of the gasoline G in the gasoline tank 1. It is configured as follows.

Although the potentiometer 7 disposed outside the gasoline tank 1 is shown in the drawing, the position of the potentiometer 7 inside or outside the gasoline tank 1 is arbitrary. Further, in the drawing, the swing arm 75, its sliding contact 75a, and the center resistance Rx are symbolized for easy viewing 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 is provided with the potentiometer 7
Input terminal Ia to which the support shaft 73 is connected, a microcomputer (CPU) 31 connected to the input terminal Ia, a nonvolatile memory (NVM) 33 and a driver 35a connected to the microcomputer 31, and a driver 35a And a fuel gauge 35 for displaying the remaining amount of gasoline in the gasoline tank 1. The input terminal Ia and the CPU 3
1 is pulled up by a pull-up power supply Vb and a pull-up resistor Rb inside the fuel gauge 3. Further, the fuel gauge 3 has an auxiliary input terminal Ib for taking in data to be written in a database constructed in the NVM 33, and a communication between the CPU 31 and an external device of the fuel gauge 3 via the auxiliary input terminal Ib. It further includes an interface (I / F) 37 for adjusting a communication format of data transmitted between them.

The CPU 31 has an A / D converter 31a for digitally converting a sender output S generated on the signal line L when the potentiometer 7 is connected to the input terminal Ia.
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 processing operations.
The OM 31c stores a control program for causing the CPU 31 to perform various processing operations.

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

The tester 9 measures a resistance value rx of a sender resistor Rx connected by a tester rod or the like while 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 linking the known amount of gasoline G and the resistance value rx at that time is stored in a buffer and stored in the 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.

The buffer includes at least link data in a state where the gasoline G in the gas tank 1 is zero, link data in a full state (in this embodiment, 70 liters), and several kinds of link data therebetween. The link data of a plurality of sets including the amount of the gasoline G stored in the gasoline tank 1 is stored and accumulated until a request from the CPU 31 is made. Then, 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 an internal memory of the tester 9 in advance, or The tester 9 is provided with input setting means (not shown) such as a ten key,
When the resistance value rx of the sender resistor Rx is stored in the buffer, the input value may be set by the input setting means.

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 is
The gasoline G is read out one by one (for example, from the state of zero gasoline G) and displayed on the display unit (not shown), and the known amount of gasoline G is stored in the gasoline tank 1 while watching the display. The measured resistance value rx of the sender resistance Rx is linked to a known amount of gasoline G read from the internal memory and stored in a buffer as link data. When inputting and setting the known amount of gasoline G from 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. An input is set, and in this state, the measured resistance value rx of the sender resistor Rx is linked to the input and set amount of the known 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 indicates the link data stored in the buffer of the tester 9 as data to be written in a database constructed in the NVM 33 via the CPU 31 via the tester 9. The connection between the support shaft 73 and the input terminal Ia is disconnected.

Next, the processing performed by the CPU 31 according to the program stored in the ROM 31c will be described with reference to the flowcharts of FIGS. When the program of the ROM 31c starts, the CPU 31 checks whether or not the auxiliary input terminal Ib is open as shown in the general flowchart of FIG. 3 (step S1), and if it is open (Y in step S1). , Step S5
If it is 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 an ignition switch (IGN) of a vehicle (not shown) is on. If not (N in step S5), the process returns to step S1 and is on. If (Step S
It is confirmed whether or not 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 performing a gasoline remaining amount measurement display process (step S9), step S1 is performed. Return to

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

The formula for calculating the remaining amount of each gasoline G is as follows.
Is determined as follows. That is, for example, the tester 9
The number of link data read from is 6
The contents of the six link data are stored in the gas
Data on the amount of Soline G [0 liter, 10 liter, 1
7.5 liters, 35 liters, 52.5 liters, 7
0 liters (full tank) and the amount of each gasoline G
, The resistance value r of the sender resistance Rx measured by the tester 9
x (re, r_Ten, R_17.5, R₃₅, R _52.5, R₇₀)
In this case, the calculation formula indicates that the resistance value rx is re ≦ rx <r
_TenRange, r_Ten≦ rx <r_17.5Range, r_17.5≦ rx <
r₃₅Range, r₃₅≦ rx <r _52.5And R
_52.5≦ rx <R₇₀5 ways to apply for each of the ranges
Becomes Then, each calculation formula defines the range of the resistance value rx as ra
When ≦ rx <rb, the remaining amount M of gasoline G =
{(Ba) · (rx-ra) / (rb-ra)} + a
Can be represented by the following general formula. Control of step S303
Once the table has been created, change the reference table to N
After being stored in the VM 33 (step S305), the main
Return to the routine. In this embodiment, the comparison table
The NVM 33 for storing the output characteristic correction data
It is equivalent to a database.

In the gasoline remaining amount measurement display processing 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 converted by the A / D converter 31a. The digital output is converted (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 S901). Step S903).

Then, the reference table is searched using the converted resistance value rx as an address pointer, and re ≦ rx
<Range of r _10, the range of _{r 10 ≦ rx <r 17.5,} r 17.5 ≦ r
a range of x <r _35, a range of r ₃₅ ≦ rx <r _52.5 , and
It is determined which of the ranges of R _52.5 ≦ rx <R ₇₀ is to be used (step S905), and the determined calculation formula is applied to calculate the remaining amount M of gasoline G in the gasoline tank 1. (Step S907), and the calculated remaining amount M
After the driver 35a drives the gauge 35 to instruct (Step S909), the process returns to the main routine. In addition, as is clear from the above description,
In the present embodiment, the signal value correcting means 31A in the claims is constituted by step S907 in the flowchart of FIG.

Next, the operation (operation) of the fuel gauge 3 of the present embodiment configured as described above will be described. Fuel gauge 3
Is incorporated into a vehicle, the support shaft 73 of the potentiometer 7 attached to the gasoline tank 1 of the vehicle is
Before connecting to the input terminal Ia of the fuel gauge 3, connect it to the positive tester bar of the tester 9 and connect the negative tester bar to
Connected to the ground terminal of the sender resistor Rx. Then, the amount of gasoline G in the gasoline tank 1 is reduced to 0 liter,
Liter, 17.5 liter, 35 liter, 52.5
Liter and 70 liters (full tank), the resistance value rx of the sender resistance Rx corresponding to the position of the float 5 in each state is measured by the tester 9, and each measured resistance value rx
Six link data linking the corresponding amount of gasoline G in the gasoline tank 1 is stored in the buffer of the tester 9.

Next, the plus and minus tester rods are
3 and the sender resistor Rx, respectively,
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 has detected that the auxiliary input terminal Ib has been closed, the six link data stored in the buffer are transferred to the CPU via the I / F 37.
31 and from the six link data, FIG.
Are created and stored in the NVM 33. The comparison table is made up of the five calculation formulas shown in FIG. At this time, if the control table is already stored in the NVM 33, the old control table is deleted and the new control table is stored.

After the above operation is completed, the support shaft 73 of the potentiometer 7 is connected to the input terminal Ia of the fuel gauge 3 and
The assembly of the fuel gauge 3 into the vehicle is completed. After that, IG
When the N switch is on, the sender output S digitally converted by the A / D converter 31a of the CPU 31
, 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 a calculation formula selected according to the resistance value rx, and the remaining amount M is indicated by the gauge 35.

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

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

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

Further, according to the present embodiment, when the CPU 31 calculates the remaining amount M of the gasoline G from the resistance value rx of the sender resistor Rx when using the fuel gauge 3 based on the link data fetched from the tester 9. The resistance value rx of the resistance value re, r ₁₀ , r measured by the tester 9 is calculated as follows.
Five types are created so as to be properly used depending on which two resistance values among _17.5 , r ₃₅ , r _52.5 , and r ₇₀ belong, and the five types of calculation formulas and the respective values are calculated when the resistance value rx is any value. The data in which the range of the resistance value rx indicating whether the equation is used is stored in the NVM 33 as the tank shape data.

For this reason, 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). according to the characteristics that the straight line connecting the resistance r ₇₀ of, as compared with the case where CPU31 calculates the remaining amount M of the gasoline G in gasoline house 1 on the basis of the resistance value rx of the sender resistor Rx to convert from the sender output S The difference between the measured remaining amount M and the actual remaining amount is reduced, and the measurement accuracy is remarkably improved, whereby 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, a highly reliable fuel gauge 3 that conforms to the internal shape and capacity of the gasoline tank 1 can be realized.

In the link data obtained in advance, the number of link data in a state where the remaining amount of the liquid G in the tank 1 is set to a remaining amount other than empty or full is 4 data ( Gasoline G amount = 10 liters,
The data is not limited to 17.5 liters, 35 liters, and 52.5 liters), but may be any value as long as it is one or more, and the numerical value of the known gasoline amount is also arbitrary. And, of course, as the number of link data increases, the number of formulas for calculating the remaining gasoline increases, and the range of values for replacing the actual sender resistance characteristics with linearity characteristics that approximates the characteristics decreases. In addition, the error of the approximate characteristic with respect to the actual characteristic is smaller, thereby further improving the accuracy of the calculated gasoline remaining amount in the tank, and having a complicated internal shape and a variety of gasoline tanks having a small capacity difference. The meter can be flexibly supported by a single configuration.

The link data may be obtained by calculation based on, for example, CAD data including numerical data such as dimensions for specifying the internal shape and capacity of the gasoline tank. Furthermore, the present invention is not limited to gasoline tanks, 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 other than a vehicle, It goes without saying that the present invention is widely applicable to various fuel gauges for measuring the remaining amount of liquid in the tank, such as a fuel tank for a combustor such as kerosene or heavy oil.

[0045]

As described above, according to the fuel gauge in the tank of the present invention, the position of the float displaced following the liquid level of the liquid in the tank is converted into an electric signal by a potentiometer. In a tank fuel gauge that measures the remaining amount of the liquid based on the arithmetic processing using the signal value of the remaining amount and the remaining amount calculation formula, the output characteristic of the electric signal by the potentiometer is set to the internal shape of the tank. An approximate characteristic database that retains data of approximate characteristics approximated to a correlation between the remaining amount of the liquid and the position of the float that are determined in accordance therewith; and correcting the signal value according to the approximate characteristics that the approximate characteristic database retains. Signal value correcting means for correcting to a signal value, wherein the arithmetic processing is performed using the corrected signal value corrected by the signal value correcting means.

For this reason, the signal value of the electric signal output from the potentiometer is calculated by the signal value correcting means on the basis of the data of the approximate characteristics held in the approximate characteristic database.
It is not proportional to the amount of rise and fall of the float, but is corrected to a correction signal value on the approximate characteristic that is proportional to the amount of increase or decrease of the liquid in the tank. , Or an accurate measurement result can be obtained based on the signal value of the electric signal output from the liquid level detection sensor irrespective of the internal shape of the tank which affects the capacity of the tank.

According to the method of constructing the database for correcting characteristics of the liquid level detecting sensor of the present invention, the electric level of the liquid level detecting sensor which outputs an electric signal of a signal value corresponding to the position of the liquid level of the liquid in the tank is provided. A method for constructing a characteristic correction database for correcting an output characteristic of a signal to a characteristic corresponding to an internal shape of the tank, the method comprising: setting a remaining amount of the liquid in the tank to a known value. The link data linking the amount and the signal value of the electric signal output by the liquid level detection sensor in accordance with the remaining amount is a state in which the tank is empty and the tank is full. And the state in which the remaining amount of the liquid is at least one remaining amount other than the empty and full tanks is obtained in advance, and based on two link data in which the signal value is adjacent among the link data. This A plurality of remaining amount calculating formulas for calculating the remaining amount of the liquid from the signal values between two adjacent signal values, and each of the remaining amount calculating formulas is used as a basis for calculating each of the remaining amount calculating formulas. Data of adjacent signal values of the two link data are managed so as to be searchable as addresses.

For this reason, when measuring the remaining amount of liquid remaining in the tank, the tank has a complicated internal shape in which the amount of increase and decrease of the liquid is not necessarily proportional to the amount of rise and fall of the liquid level. Alternatively, although the amount of increase and decrease of the liquid and the amount of rise and fall of the liquid level are proportional to each other, even if the capacity when the tank is full differs depending on the type, based on the output of the single structure liquid level detection sensor, the actual It is possible to obtain a highly accurate remaining amount approximate to the remaining amount in the tank by calculation, and it is possible to obtain effects such as being suitable for use in the remaining amount meter in the tank of the present invention.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram showing a schematic configuration of a fuel gauge according to an embodiment of the present invention by partial blocks.

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 illustrating a subroutine of a tank shape database creation process of FIG. 3;

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

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

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

[Explanation of symbols]

 DESCRIPTION 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 level

Claims (4)

(57) [Claims] 1. A position of a float which is displaced following a liquid level of a liquid in a tank is converted into an electric signal by a potentiometer, and is calculated based on a signal value of the electric signal and a remaining amount calculation formula. In the in-tank fuel gauge for measuring the remaining amount of the liquid, the output characteristic of the electric signal by the potentiometer, the correlation between the remaining amount of the liquid determined according to the internal shape of the tank and the position of the float. An approximation characteristic database that retains data of approximated approximation characteristics; a selection target table that retains a calculation formula used to measure the remaining amount of liquid in the tank based on the data retained in the approximation characteristics database; and the potentiometer The signal value of the electrical signal output by
Nearly proportional to the amount of increase or decrease of the liquid in the tank according to the data of the approximate characteristics held by the approximate characteristic database.
And a signal value correction means for correcting the correction signal on the similar characteristics, collates the corrected correction signal and said selection object table by the signal value correction means, corresponding to the data to be approximate to the correction signal liquids Use the remaining amount calculation formula from the selection target table
The tank remaining amount gauge is characterized in that the remaining amount of liquid in the tank is calculated by performing a search . 2. A pre-SL signal value correction means, according to claim 1 for correcting the signal value in the course of the arithmetic processing on the corrected signal value
The fuel gauge in the tank as described. 3. An output characteristic of the electric signal of a liquid level detection sensor that outputs an electric signal of a signal value according to a position of a liquid level of a liquid in a tank is corrected to a characteristic according to an internal shape of the tank. A method for constructing a characteristic correction database for storing a remaining amount of the liquid in a state where the remaining amount of the liquid in the tank is known, and outputting the liquid level detection sensor in accordance with the remaining amount. Link data linking the signal value of the electric signal is a state in which the tank is empty, a state in which the tank is full, and a state in which the remaining amount of the liquid is at least one other than empty and full. The state of the remaining amount is obtained in advance, and based on two link data in which the signal value is adjacent to each other in the link data, the remaining amount of the liquid is determined from the signal value between these two adjacent signal values. To calculate the amount A plurality of remaining amount calculation formulas, and the respective remaining amount calculation formulas are managed so as to be searchable as addresses of adjacent signal values of the two link data based on which the respective remaining amount calculation formulas are calculated. A method for constructing a database for correcting characteristics of a liquid level detection sensor, characterized in that: 4. The link data is obtained by storing a known amount of the liquid in the tank and actually measuring a signal value of the electric signal output by the liquid level detection sensor in this state. A method for constructing a database for correcting characteristics of a liquid level detection sensor according to claim 3.