JPH0534185A - Fuel residual quantity meter for vehicle - Google Patents

Abstract

PURPOSE:To calculate the accurate residual quantity of fuel by a method wherein the detection values of the residual quantity of the fuel in a fuel tank are sampled for a predetermined time and averaged to calculate the differences between the averaged value and the sampled detection values and it is judged which range the differences belong to. CONSTITUTION:A sensor 1 outputs the change of the liquid level in a fuel tank 11 to an A/D converter and the digitally converted detection value is stored in a shift register 3 at every predetermined time. The shift register 3 constituted of (n) registers stores the newest detection value and shifts the respective detection values stored up to now to the adjacent registers. An averaging circuit 4 averages the detection values at every predetermined time and a liquid level change judging circuit 5 to compare the averaged value with the respective detection values up to the next predetermined time to calculate respective differences and calculates which of a plurality of predetermined ranges how many differences belong to and the variable determined according to the range to which the most number of differences belong is selected. An operation circuit 6 performs operation using this variable and the average value of the circuit 4 to measure residual quantity. By this constitution, residual fuel can be accurately judged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle fuel level gauge capable of accurately measuring the amount of fuel remaining in a fuel tank.

[0002]

2. Description of the Related Art Japanese Patent Publication No. 2-37966 and Japanese Patent Publication No. 3-3961 disclose known devices of this type.
There is publication No. 8. These have means for detecting the remaining amount of fuel in the fuel tank, sampling the detected values in time series, and performing the averaging process of these sampled detected values to obtain the remaining amount value. However, even if there is a large change in the detected value due to running on a rough road, in order to prevent the detected value from changing unnecessarily, the detected values due to the large changes are averaged. The process of sampling the value again is also performed.

[0003]

By the way, the fluctuation in the fuel tank is not limited to traveling on a bad road, but also appears in the case of refueling. The fluctuations in the case of running on the rough road must be dealt with so as not to affect the processing circuit that follows, whereas that during refueling must be rapidly transmitted to the processing circuit.

However, at the time of refueling, as described above, if the process of averaging the detected values having a certain fluctuation range and sampling again, a large fluctuation must be transmitted to the circuit in the subsequent stage as it is. It was reduced by the value before refueling that was previously sampled,
There will be some delay in the change time.

[0005]

SUMMARY OF THE INVENTION The present invention comprises a detecting means for detecting the remaining amount of fuel in a fuel tank, and a sampling means for sampling the detected value of the detecting means at predetermined time intervals.
Averaging means for averaging the sampled detection values,
The average value processed by the averaging means is compared with the sampled detection value to obtain respective differences, and it is determined to which of a plurality of predetermined ranges these differences belong, the difference Is provided with a determining means for selecting a variable prepared in a predetermined range to which the most belongs and an arithmetic means for obtaining the remaining fuel amount from this variable.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention is shown in FIGS.

The sensor 1 converts the fluctuation of the liquid level due to the floating in the fuel tank 11 into an electric change of a variable resistor (not shown) and outputs it to the A / D converter 2. The detected values converted into digital values are stored in a plurality of prepared shift registers 3 every predetermined time. The shift register 3 is composed of n registers 31 to 3n, and stores the latest detected value at each predetermined time and shifts the detected values of the registers 31 to 3n stored so far to the adjacent register. It Further, the averaging circuit 4 performs processing for averaging the detection values of the register 3 every predetermined time. The liquid level fluctuation determination circuit 5 is a circuit that performs the main processing of the present application. The determination circuit 5 compares the detected values of the registers 31 to 3n with the averaging circuit 4 between the predetermined time and the next predetermined time, calculates the respective differences, and calculates the difference between them. It is a circuit that calculates how many and which of a plurality of predetermined ranges belongs to which range, and selects the variable defined by the range to which the most belongs. The arithmetic circuit 6 uses the selected variable and the average value of the averaging circuit 4 to obtain f (m) = f (m-1) + (AV-f (m-1)) / R where f (m ) Current output value f (m-1) Previous output value AV average value The R variable is calculated to measure the remaining amount, and data is transmitted to the display 7 etc. based on this value.

A detailed description will be given below with reference to FIG. For example, the liquid level fluctuation determination circuit 5 includes three predetermined ranges α, β, γ.
Are set, and they are "a or less", "a or more and b or less",
Assuming that the difference is “b or more” (a <b), it is calculated which of the predetermined ranges α, β and γ the difference between the average value AV and each register 31 to 3n belongs to most, and as a result, the variable R1, R2
It is assumed that any one of R3 (R3 << R1 <R2) is selected.

When the vehicle is traveling on a relatively flat road surface and the fluctuation of the liquid level is small, there is almost no difference between the detected values of the registers 31 to 3n, and therefore the average value AV of the averaging circuit 4 is set.
And a comparison process 51 for comparing the detected values of the registers 31 to 3n with each other.
The determination is made so that the count value of C1 in the count processing 52 is counted up most because there is almost no difference from these values. As a result, R1 is selected as the variable R, and then this variable R1 is output to the arithmetic circuit 6 in the subsequent stage. This R1 is set to a relatively small value, and the difference between the average value of the second term of the above-mentioned arithmetic expression and the previous output is not changed as much as possible and it is attempted to be added to the first term. For example, if R1 is set to "1", the arithmetic expression becomes f (m) = AV, and the arithmetic operation is performed assuming that the output is only averaged so that the output value is easily changed.

Next, when the vehicle is traveling on a rough road and the liquid level is drastically changed, the difference between the detected values of the registers 31 to 3n and the average value AV obtained by averaging them by the averaging circuit 4 is considerably large. It is expected that the count value of C2 in the count process 52 is counted up most. As a result, R2 is selected as the variable R and predetermined arithmetic processing is performed in the arithmetic circuit 6, but R2 is set larger than R1 and is a variable that reduces the second term of the arithmetic expression. For example R
When the value of 2 is infinite in the extreme case, the arithmetic expression becomes f (m) = f (m-1), and the output value does not change.
That is, when the liquid level fluctuations such as running on a rough road are severe, the output value is processed as little as possible.

Further, in the case of refueling, the fluctuation of the liquid level is also severe in this case, but it must be handled as a special case. At the beginning of refueling, the detection value of the shift register 3 is a stable detection value that is obtained during traveling and has a smaller fluctuation than the fluctuation at the time of refueling, and the averaging circuit 4 averages these detection values. When the comparison processing 51 of the converted average value AV and the detected values of the registers 31 to 3n is performed, the count processing 52 counts up C1 most because the average value AV is still small. Therefore, at this point in time, the liquid level variation determination circuit 5 cannot determine that the fuel is being refueled,
The output value is changed according to the processing described above. However, if refueling continues, the sampled detection values of the registers 31 to 3n will suddenly increase. Along with this, the average value AV also increases, but since the average value AV is the average of the registers 31 to 3n, the difference between the relatively new sampled detection value and the average value AV and the relatively old sampling The difference between the detected value and the average value AV becomes very large, and as a result, in the count processing 52, the count-up of C3 is performed most and the variable R3 is selected. This variable R3
Is a value smaller than R1, and as a result, the second
The influence of the term is largely exerted on the first term to promptly prompt the change of the output value, and the output value can follow the rapid change of the liquid level of the oil supply.

That is, since the variables of the arithmetic expression are selected according to the fluctuation of the liquid surface and the output value is calculated in accordance with the situation, an appropriate fuel remaining amount can be obtained.

In this embodiment, the value of the variable R and the width of the predetermined range can be changed appropriately. For example, R3 is a variable provided for the case of refueling, but if this process is not necessary, it may be adopted as a process for simply dealing with the liquid level fluctuation during traveling, and the point is that the true fuel remaining amount is required. It suffices to be able to perform processing so that a value far from the quantity is not detected as an output value.

[0014]

According to the present invention, a detecting means for detecting the remaining amount of fuel in the fuel tank, a sampling means for sampling the detected value of the detecting means at every predetermined time, and an averaging means for averaging the sampled detected values, The average value processed by the averaging means is compared with the sampled detection value to obtain respective differences, and it is determined to which of a plurality of predetermined ranges these differences belong, the difference Is provided with a determining means for selecting a variable prepared in a predetermined range to which most of the values belong, and a calculating means for obtaining the fuel remaining amount from this variable, thereby determining a value far from the true fuel remaining amount. It is possible to perform processing that is not detected as an output value.

[Brief description of drawings]

FIG. 1 is a diagram showing a block diagram of the present invention.

FIG. 2 is a flow chart showing the main processing of the present invention.

[Explanation of symbols]

 1 Detecting Means (Sensor) 11 Fuel Tank 3 Sampling Means (Shift Register) 4 Averaging Means (Averaging Circuit) 5 Judging Means (Liquid Level Fluctuation Judging Circuit) 6 Arithmetic Means (Arithmetic Circuits)

Claims (1)

Claim: What is claimed is: 1. A detection means for detecting the amount of fuel remaining in a fuel tank, a sampling means for sampling the detection value of the detection means at predetermined time intervals, and averaging the sampled detection values. Averaging means, the average value processed by this averaging means and the sampled detection value are compared to obtain respective differences, and which range of a plurality of predetermined ranges these differences belong to is determined. A vehicle fuel level meter, comprising: determination means for determining and selecting a variable prepared in a predetermined range to which the above-mentioned difference most belongs, and calculation means for determining a fuel remaining amount by this variable.