JPH0410013B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel consumption measuring device for an automobile, and more particularly to a fuel consumption measuring device that calculates the amount of fuel consumed from the opening time of a fuel injection valve.

Conventionally, liquid level detection means such as a float sensor installed in the fuel tank, or a flow meter installed in the fuel piping, etc., have been used as a means of checking the amount of fuel consumed by a car, but recently they have become widespread. In automobiles equipped with a certain fuel injection system, a fuel consumption measuring device that calculates the amount of consumed fuel from the opening time of the fuel injection valve is widely used, for example as shown in Japanese Utility Model Application No. 55-49293. It is used. Of course, such a fuel consumption measuring device can be used normally to check the remaining amount of fuel, but it can also easily measure the instantaneous amount of fuel consumed.
It is also widely used to display various fuel-related functions, such as displaying the instantaneous amount of fuel consumed and calculating and displaying fuel consumption over a short period of time by connecting it to a microcomputer.

However, the actual fuel injection amount of each fuel injection valve often differs from the nominal value due to manufacturing errors, changes over time, etc. If there is an error in the fuel injection amount in this way, the unit of the fuel injection valve Naturally, the consumed fuel amount obtained by multiplying the injection amount per hour by the valve opening time is also inaccurate. The error in the fuel injection amount is, of course, minute, but as the amount of fuel consumed is measured, for example, as much as one fuel tank, the error in the fuel consumption amount increases considerably. Alternatively, the reliability of the display of the amount of consumed fuel or the remaining fuel amount decreases in a region where the remaining fuel amount is desired to be displayed.

The present invention has been made in view of the above circumstances, and is capable of accurately calculating the amount of fuel consumed.
The object of the present invention is to provide a fuel consumption measuring device that integrates the opening time of a fuel injection valve.

The fuel consumption measuring device of the present invention converts the consumed fuel amount by multiplying the opening time of the fuel injection valve by a conversion coefficient determined from the injection amount per unit time of the fuel injection valve. In the fuel measuring device, first and second liquid level sensors are installed at appropriate locations in the fuel tank to detect the height of the fuel level at two locations, and signals from these first and second level sensors are input. Then, calculate the actual amount of fuel consumed during the period when the liquid level in the fuel tank fluctuates between these two sensors, calculate the ratio of this actual amount of fuel consumed and the equivalent amount of consumed fuel corresponding to the actual amount of consumed fuel, and calculate the amount of fuel consumed. a calculation means that multiplies the conversion coefficient by the ratio and changes it to a new conversion coefficient; and a correction calculation of the calculation means (calculation that changes the conversion coefficient) when the fuel lid is opened when the liquid level is located between the two sensors. The invention is characterized in that it is provided with a canceling means for canceling.

By providing the calculation means as described above and changing the conversion coefficient based on the actually measured amount of consumed fuel, subsequent fuel consumption measurements can be performed with complete accuracy. Moreover, since the above conversion coefficient is changed by making corrections in subsequent measurements to account for the error in the converted consumption amount, it is possible that the injection amount of the fuel injection valve will gradually change due to aging. Even if there is a problem, the conversion factor is changed accordingly, so that the fuel consumption amount is always calculated accurately. Furthermore, if the above-mentioned canceling means is provided, the conversion coefficient will not be changed when refueling is performed while the actual amount of fuel consumed is being measured, so it is possible to prevent incorrect conversion coefficients from being set. .

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 schematically shows the configuration of a fuel consumption measuring device for an automobile according to an embodiment of the present invention. A reference pulse So consisting of a constant frequency clock pulse generated by the pulse generator 1 and an injection pulse S for instructing the fuel injection device 2 to open the fuel injection valve are input to the AND gate 3. This AND gate 3 is connected to these reference pulses.
The reference pulse So is passed only when both So and the injection pulse S are input. Therefore, the reference pulse that passed through this AND gate 3
By counting So with the counter 4, the opening time (integrated amount) of the fuel injection valve can be determined. The arithmetic circuit 5 converts the amount of consumed fuel based on the valve opening time signal inputted from the counter 4. This fuel consumption conversion is performed as shown in the flowchart of FIG. First, calculate the valve opening time cumulative value T from the valve opening time signal, and calculate the valve opening time cumulative value T.
is multiplied by a conversion coefficient k determined by the injection amount per unit time of the fuel injector to obtain the converted fuel consumption amount Q.
(This conversion factor k is the previous conversion factor
ko multiplied by the correction coefficient C; this point will be explained in detail later). By subtracting the amount of consumed fuel Q obtained in this way from the full capacity V of the fuel tank, the remaining fuel amount V _F is obtained, and the remaining fuel amount V _F
can be shown on the display device 6.

The above calculations are commonly performed in conventional fuel consumption measuring devices of this type, but in the device of this embodiment, there are two liquid level sensors that actually measure the amount of fuel in the fuel tank. 7 and a remaining amount switch 8 are provided, and the conversion coefficient k is corrected as described above based on the actual amount of consumed fuel actually measured by these liquid level sensors. This point will be explained in detail below.

The full tank switch 7 is turned off when the remaining fuel level is V ₁ or more, which makes the fuel tank almost full, and is turned off when it is less than V ₁ .
The remaining amount switch 8 outputs an ON signal, and outputs an OFF signal when the remaining fuel amount is less than V ₂ and is ON when the fuel tank is relatively empty and the remaining fuel amount is less than V ₂ . Naturally, V ₁ > V ₂ here. The output signals of the full tank switch 7 and the remaining switch 8 are sent to discrimination circuits 9 and 1, respectively.
It is input to the arithmetic circuit 5 through 0. These discrimination circuits 9 and 10 are used for the full tank switch 7 and the remaining tank switch 8.
If the output signal from the switch is the same continuously for a predetermined period of time, that signal is sent to the arithmetic circuit 5 as an output signal from each switch,
By providing such discrimination circuits 9 and 10, temporary fluctuations in the fuel level due to fuel consumption, for example, when a car is running on a slope or when it bounces after running over a stone, etc., can be ignored. It becomes possible to distinguish this from liquid level height fluctuations. As shown in the flowchart of FIG.
Converted fuel consumption when changing from OFF to ON Q ₁
Using the converted fuel consumption _Q2 when the output signal of the remaining fuel switch 8 changes from OFF to ON, C=
A value C of V ₁ −V ₂ /Q ₂ −Q ₁ is determined (the fuel lid will be described later). This value C is the actual amount of fuel consumed (V ₁ - V ₂ ) between the detected liquid level height of the full tank switch 7 and the detected liquid level height of the remaining amount switch 8, and the period of time during which these two liquid level heights are detected. This is the ratio of the converted fuel consumption amount (Q ₂ - _{Q 1} ) that was converted to . Figure 4 explains the correction of the conversion coefficient k, and as is clear from this Figure 4, C=V ₁ -V ₂ /Q ₂ -Q ₁ =Tm/Tko=m/k
o (m is the correct conversion coefficient for the fuel injection valve), and when the previous conversion coefficient ko is multiplied by the above C (=m/ko) as a correction coefficient, C.ko=m is obtained, and the correct conversion coefficient is obtained. Therefore, as shown in the flowchart of FIG. 2, by using the conversion coefficient k=C.ko obtained in this manner, the amount of fuel consumed can be accurately converted.

The above conversion coefficient k=C・ko is calculated at the time when the remaining amount switch 8 detects the liquid level height, so if the conversion coefficient is corrected immediately at this point, the subsequent fuel consumption conversion will be is performed as shown by straight line a in FIG. By storing this corrected conversion coefficient k in the memory 11 and using this conversion coefficient k in the next measurement, correct fuel remaining amount display can be performed from the beginning.

Before the first calculation, C=1 is stored, but since the measurement error before the first correction of the conversion coefficient k is naturally large, the fuel The remaining amount may not be displayed. Furthermore, even after the first correction is applied, the previous error E (see Figure 4) remains, but once the conversion coefficient k is corrected, the fuel tank will receive the next refueling within a short time. Considering that the next fuel consumption measurement will be performed correctly from the beginning, this error E will not be a serious problem.

Additionally, in this device, there is a fuel lid switch 1 that detects the opening of the fuel lid of the fuel supply port.
2 is provided, and this fuel lid switch 12
The output signal of is also input to the arithmetic circuit 5. In other words, if fuel is refilled after the fill switch 7 is turned on and before the remaining fuel switch 8 is turned on, it will be impossible to determine the correct correction coefficient C, so if the fuel lid is opened during this time, Then, as shown in Fig. 3, the arithmetic circuit 5
cancels the correction calculation and uses the conventional conversion factor.
It only converts the amount of fuel consumed using ko and only displays the value.

Since it is impossible for the full tank switch 7 to be OFF and the remaining battery switch 8 to be ON, an AND gate 13 and an EX-OR gate 14 are provided, and if such a signal is issued from both switches 7 and 8, A failure signal is input to the arithmetic circuit 5. When this failure signal is input, a failure indication is displayed on the device, and the calculation of the correction coefficient C is canceled, and thereafter only the amount of consumed fuel is displayed.

The correction of the conversion coefficient k as explained above may be performed every time the fuel tank is fully refilled, and taking into account that the characteristics of the fuel injection valve will not change suddenly. For example 10
It may be performed intermittently, such as once every time the oil is refilled. When the arithmetic circuit 5 is composed of a microcomputer, such an instruction to perform the correction can be easily and automatically made by inputting the number of times of refueling from the fuel lid switch 12, for example. In addition, the two fuel level heights detected for actual measurement of the amount of consumed fuel are set at two locations, one near the full fuel tank and one near zero remaining fuel, as in the above example. Although two liquid level heights may be used, if two liquid level heights with a large difference as in the above embodiment are used, the accuracy of the actual measurement of the consumed fuel amount will be improved accordingly. Furthermore, in the embodiment described above, a part of the canceling means is incorporated in the arithmetic circuit 5; is input to a separate discrimination circuit, and both switches (sensors)
When a lid open signal is issued from the fuel lid switch 12 when the liquid level is between 7 and 8, the discrimination circuit sends a cancel signal to the calculation circuit to cancel the correction calculation. It's okay.

As explained in detail above, the fuel consumption measuring device of the present invention is capable of accurately converting the amount of fuel consumed according to individual characteristics even if there are variations in the characteristics of fuel injection valves. As a result, it is no longer necessary to precisely measure the conversion coefficient through experiments, and cost reductions can be expected. Furthermore, since the conversion coefficient is corrected to match the actual characteristics of the fuel injection valve, even if the injection amount changes due to aging of the fuel injection valve, a correct converted fuel consumption amount can always be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention;
Fig. 2 is a flowchart showing the process of converting the amount of fuel consumed in the embodiment of Fig. 1, and Fig.
FIG. 4 is a flow chart showing the process of correction calculation in the embodiment shown in the figure, and FIG. 4 is a graph showing the effect of the conversion factor correction in the embodiment shown in FIG. 2...Fuel injection device, 4...Counter, 5...
Arithmetic circuit, 7... Full tank switch, 8... Remaining level switch, 12... Fuel lid switch, S...
...Injection pulse, So...Reference pulse.

Claims (1)

[Claims] 1. A fuel consumption measuring device for an automobile that integrates the opening time of the fuel injection valve and displays the converted fuel consumption amount obtained by multiplying this integrated time by a conversion coefficient, and is installed at two positions, upper and lower, at appropriate locations in the fuel tank. A first and second liquid level sensor that detects the fuel level, respectively, and signals from these first and second liquid level sensors are input, and the liquid level of the fuel tank is determined between these two sensors. Find the actual amount of fuel consumed during the period in which the liquid level changes, take the ratio of the actual amount of fuel consumed between these liquid level sensors and the converted amount of consumed fuel corresponding to this actual amount of consumed fuel, and multiply this ratio by the conversion coefficient. A calculation means for performing a correction calculation to change the conversion factor to a new conversion factor, and a canceling means for canceling the correction calculation of the calculation means when the fuel lid is opened when the liquid level is located between the two sensors. Features: Automotive fuel consumption measuring device.