JPH0216264Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to fuel efficiency meters attached to internal combustion engines such as automobiles, and more specifically, to fuel efficiency meters that display the amount of fuel remaining in the fuel tank. The present invention relates to a full tank set device used.

<Prior art> In modern automobiles, the cumulative value of the amount of fuel consumed by the internal combustion engine is calculated, and based on this calculated data, the amount of fuel remaining in the fuel tank and the future driving are determined based on the amount of fuel remaining in the fuel tank. There is one that calculates and displays the possible distance.

That is, the amount of fuel remaining in the fuel tank is determined by sequentially cumulatively decreasing the consumption amount measured by the flow meter from the initial amount of fuel in the tank. For the initial fuel amount above, use the state where the tank is filled with fuel (this is called a full tank) as the tank capacity, which has a fixed value, and reset the fuel consumption meter (set to full tank) with the tank full. , starts the residual amount calculation operation.

Conventional fuel efficiency meters are equipped with a manual switch called a fill-up switch, which is pressed when the tank is filled to the full and the tank is manually set to full.

<Problems to be solved by the invention> With the above-mentioned conventional fuel efficiency meter, it is necessary to operate a switch every time the tank is filled with fuel, and if this is forgotten, the amount of remaining fuel cannot be calculated.

Therefore, it is conceivable to use a conventionally provided float mechanism of a fuel meter and set the tank to full by having the float lever push a limit switch when the float reaches the upper limit.

However, with this full-tank setting device, when the liquid level in the tank fluctuates due to driving on rough terrain, etc., the limit switch easily activates repeatedly, and if the switch signal is used as the fuel gauge reset signal, the tank will not be full. There is also a risk that it may be reset. This is because the stroke amount after the limit switch is activated is very small, and a slight fluctuation in the fuel level causes a chattering-like operation.

The present invention was developed in view of the above-mentioned problems, and its purpose is to provide a simple configuration that utilizes a float mechanism inside the tank, and to provide a highly reliable full tank signal without causing malfunctions due to fluctuations in the liquid level. An object of the present invention is to provide a full-tank setting device that allows

<Means for solving the problem> For this reason, the present invention calculates the amount of fuel consumed from when the amount of fuel in the fuel tank is full, and calculates the remaining amount of fuel in the fuel tank based on the calculated data. A fuel consumption meter that displays fuel consumption, etc., has a float that is attached to a lever and rotates to follow the fuel level in the fuel tank, and a resistance value that changes depending on the amount of rotation of the lever, so that the fuel level is close to full. A variable resistor that is set so that the rate of change in resistance value with respect to the amount of rotation of the lever is small when When the voltage Vx exceeds the reference voltage Vt, it is inverted to either high level or low level, and the voltage Vx is the value Vt obtained by subtracting a predetermined hysteresis amount ΔV from the reference voltage Vt. The comparator includes a comparator with hysteresis in the input/output change characteristic that returns to the other level when the voltage falls below -ΔV, and outputs a full set signal by inverting the comparator from the other level to the one level. and a full tank setting means for starting calculation of the fuel consumption amount.

<Function> In the above configuration, when the tank is full, the voltage Vx generated corresponding to the resistance value of the variable resistor
exceeds the reference voltage Vt, the output of the comparator is inverted, and a full tank is automatically set.

In addition, when the resistance value of the variable resistor is close to full, the rate of change with respect to the amount of rotation of the lever is set to be small, and the comparator is set so that when the voltage Vx exceeds the reference voltage Vt, Input/output change characteristic that inverts to either high level or low level and returns to the other level when voltage Vx falls below the value Vt - ΔV obtained by subtracting a predetermined hysteresis amount ΔV from reference voltage Vt. Because of the hysteresis, small fluctuations in the fuel level will not cause the comparator to flip from one level to the other.

Therefore, even if there is a slight change in the fuel level, the full tank set signal will not be output due to the reversal, so there is no risk of resetting.

<Example> FIG. 1 shows an example of a float mechanism provided in a fuel tank. Incidentally, this float mechanism is well known as a sender unit of a fuel meter.

As shown in the figure, the base end of a lever 10 is attached to the top of the fuel tank so as to be rotatable about a shaft 12, and a float 14 is attached to the tip of the lever 10.
is installed. The float 14 moves up and down following the liquid level 16 in the tank, and the lever 10 rotates up and down about the shaft 12.

A sliding resistance plate 18 is attached near the base end of the lever 10 and rotates together with the lever 10. On the other hand, the contact plate 20 that slides relatively on the surface of the sliding resistance plate 18 is located on the fixed base side.
It is attached together with 2. One end of the sliding resistance plate 18 is connected to terminal A by a flexible lead wire 22, and the contact plate 20 is connected to terminal B. The above is the configuration of the variable resistor 24 interlocked with the lever 10.

Position of lever 10 and resistance value of variable resistor 24
The relationship with Rx is shown in the graph of Figure 2.

In this embodiment, as the fuel level 16 becomes higher, the resistance value Rx increases, and the rate of increase becomes smaller in the region where the resistance value is high. Rx1 in the figure is a resistance value at a full tank set level, which will be described later.

FIG. 3 shows the configuration of the electric circuit of the tank filling device according to the present invention.

The variable resistor 24 is connected to a DC power supply in series with the resistor R1, and the voltage Vx at the connection point between the two is applied to the + terminal of the comparator 26. Further, reference resistors R2 and R3 are connected in series to the DC power source, and a predetermined reference voltage Vt obtained from the connection point between the two is applied to the - terminal of the comparator 26.

The comparator 26 has hysteresis in the input/output change characteristics, and in particular, the hysteresis width ΔV is selected to be sufficiently large. Resistance value of variable resistor 24
When Rx exceeds the full tank level Rx1, the above voltage
When Vx exceeds the reference voltage Vt, the output of the comparator 26 is inverted from the "L" level to the "H" level. This output change is a full tank set signal, which is outputted by a full tank set means (not shown), and the fuel consumption meter starts calculating the amount of fuel consumed.

When the input voltage Vx at the + terminal of the comparator 26 falls below (Vt-ΔV), the output of the comparator 26 returns from the "H" level to the "L" level. In other words, it shows a hysteresis characteristic with a hysteresis width ΔV. Resistance value Rx corresponding to this hysteresis width ΔV
The range of change ΔR is shown in Figure 2.

As shown in the figure, when the resistance value Rx becomes less than (Rx1 - ΔR), the output of the comparator 26 becomes "L" level.

The above hysteresis characteristic creates a large operating margin (ΔS in FIG. 2) regarding the position of the lever 10. That is, when the lever 10 reaches the position P and the output of the comparator 26 goes to the "H" level, the output of the comparator 26 does not return to the "L" level unless the lever 10 goes down to the position Q, which is lower than that by ΔS. Moreover, once it falls below position Q, it will not become "H" unless it reaches position P again. This ΔS becomes extremely large because the hysteresis width ΔV of the comparator 26 is large and the rate of change of the resistance Rx becomes small in the high resistance region. Therefore, even if the fuel level 16 fluctuates somewhat, the comparator 26 will not malfunction in a chattering manner.

Note that the voltage signal generated by the variable resistor 24
If Vx is configured to be input to the comparator 26 through a smoothing circuit with an appropriate time constant, fluctuations in the liquid level 16 will be averaged out, making malfunctions more difficult.

<Effects of the invention> As explained in detail above, the fuel consumption meter full tank setting device according to the present invention has a simple configuration using a float mechanism, but the resistance value against the amount of rotation of the lever near the full tank is small. A variable resistor that is set to reduce the rate of change in the fuel level and a comparator that has hysteresis in the input/output change characteristics are used, so even slight fluctuations in the fuel level will not cause the full tank signal to be output. , chatter can be avoided.

As a result, high reliability can be ensured in the fuel consumption calculation started by the output of the full tank set signal.

In addition, after the device according to the present invention detects the full tank state, the remaining amount of fuel is calculated from the consumption amount, so even if the fuel tank has a complicated shape, it will not be difficult to create it. Does not affect accuracy.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a float mechanism in an embodiment of the present invention, FIG. 2 is a characteristic diagram of the variable resistor shown in FIG. 1, and FIG. 3 is a block diagram of an electric circuit in the same embodiment. 10...Lever, 14...Float, 24...
Variable resistor, 26... comparator.

Claims (1)

[Scope of utility model registration request] A fuel consumption meter that calculates the amount of fuel consumed from a full fuel tank and displays the remaining amount of fuel in the fuel tank based on the calculated data is attached to a lever and measures the amount of fuel in the fuel tank. The float rotates to follow the liquid level, and the resistance value changes depending on the amount of rotation of the lever, and when the fuel level is near full, the rate of change in resistance value with respect to the amount of rotation of the lever becomes small. Compare the variable resistor set as follows, the voltage Vx generated corresponding to the resistance value of this variable resistor, and the reference voltage Vt corresponding to the full tank state, and when the voltage Vx exceeds the reference voltage Vt. An input/output change that inverts to either a high level or a low level and returns to the other level when the voltage Vx falls below the value Vt - ΔV obtained by subtracting a predetermined hysteresis amount ΔV from the reference voltage Vt. Full-tank setting means comprising a comparator having characteristic hysteresis, and outputting a full-tank setting signal to start calculation of the fuel consumption amount when the comparator is inverted from the other level to the one level. A device for setting a full tank of a fuel consumption meter.