JP2002168676A - Fuel detector for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel detector for a vehicle capable of accurately detecting fuel. SOLUTION: The fuel detector for the vehicle comprises two resistor type sensors 1 and 2, having movable contacts 1S and 2S disposed at different positions in the fuel tank of the vehicle. Resistors RT1 and RT2 are connected in parallel with an on-vehicle power source E for obtaining an output voltage V1, corresponding to a detected resistance value RM by the contact position of the contact 1S of the resistor RT1 of the sensor 1, and an output voltage V2 corresponding to a detected resistance value RS by the contact position of the contact 2S of the resistor RT2 of the sensor 2. Furthermore, in order to combine these outputs, an output resistor (r) having a large resistance value is connected to the outputs of the contacts 1S and 2S to connect its output, so as to obtain an output voltage VO proportional to the fuel residue. A regulating resistor RG is connected in series with a smaller one of the resistance values of the resistors, so that RT1=RT2+RX holds.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel detecting device for a vehicle equipped with a fuel tank.

[0002]

2. Description of the Related Art A vehicle running on fuel such as gasoline or methanol is equipped with a fuel tank for storing fuel, and an engine is driven by supplying fuel from the fuel tank. A fuel indicating instrument to be installed is installed on the dashboard in front of the driver's seat, and the driver confirms this to determine that there is a fuel shortage and refuel the fuel.

As such a fuel indicating instrument for indicating the remaining fuel amount in the fuel tank, there are a cross-coil type instrument or a stepping motor type instrument which indicates with a pointer, a liquid crystal display which indicates with a bar graph or a digital value. A liquid level sensor in which a resistance type sensor having a simple structure and a low-cost configuration is installed in a fuel tank is generally known as a device for detecting the remaining amount of fuel in the tank using a fluorescent lamp or a fluorescent display tube. The driver can always check the fuel level indicated by the fuel detection device at the driver's seat during driving, and can determine the necessity of refueling according to the distance to the destination.

In the fuel tank structure of a vehicle, for example, the average liquid level is detected in one tank in consideration of the liquid level inclination due to the inclination of the vehicle.
And Japanese Patent Publication No. 2-38830, which discloses an arrangement in which two liquid level sensors are arranged in a tank as disclosed in Japanese Patent Application Publication No. JP-A-2003-38830, and a motorcycle-type saddle-type tank. A tank that is based on the average output of two liquid level sensors provided in each of the separation chambers (main tank, sub-tank, or reservoir tank) in a two-compartment tank that communicates with each other. In some cases, two liquid level sensors are arranged at different positions inside the tank, and the detection results of each liquid level sensor are combined to obtain a substantial fuel amount in the tank.

[0005]

However, in the detection of the remaining amount of fuel by the two resistive sensors, the movable contact is rotated at an angle by an arm connected to a floating float according to the liquid level, and is connected to a resistor. The resistance value corresponding to the liquid level is determined by the voltage at the connection position with many electrodes, but the resistance value of the resistor of these two resistive sensors is used especially in the main tank and sub tank. In many cases, the floats are designed differently depending on the difference in the magnitude of vertical movement of the float according to each tank capacity, and when these are simply connected in series and detected by their series combined resistance, for example, RM is the sensor detection resistance of
Assuming that the other sensor detection resistor is RS, the combined resistance RM + RS is proportional to the remaining amount of fuel. However, in actuality, a detection structure in which sensors are simply connected in series requires an ammeter to be connected in series to this circuit. If the indicating instrument is controlled digitally like a microcomputer,
It is required to detect the sensor output by voltage.

Further, in the above-described series connection structure, since a large current flows through the movable contact, the Ag (silver) component of the electrode and the contact is particularly deteriorated in fuel such as gasoline due to the sulfur content in the fuel. Sulfidation causes the silver sulfide to accumulate on the electrodes and contact surfaces, increasing the electrical resistance between the contacts and affecting the current flowing between the contacts. In this case, a voltage proportional to the remaining amount of fuel can be obtained, and a large current does not flow through the movable contact, thereby reducing problems such as sulfuration at the contact portion. Attempts have been made to prepare a type sensor and connect the outputs of the movable contacts to obtain a combined output. For example, a configuration as shown in FIG.

That is, the output voltage corresponding to the detected resistance value RM based on the contact position of the movable contact 1S of the resistor RT1 of the one resistive sensor 1 with respect to the power supply E is V1, and the resistor RT2 of the other resistive sensor 2 is the same. The output voltage corresponding to the detected resistance value RS according to the contact position of the movable contact 2S in V2 is set to V2, and an output resistance r having a large resistance value is connected to each movable contact output in order to combine the outputs, and the output is connected. When trying to obtain an output voltage VO proportional to the remaining amount of fuel, the output voltage VO is expressed by the following equation. If the resistance value of the output resistance r is set to a sufficiently large value compared to the sensor resistances RM and RS, the output voltage of each of the sensors 1 and 2 does not interfere because almost no current flows. By keeping
Since the output voltage at the connection point maintains the middle point of each sensor output, VO = (V1 + V2) / 2 = ((E / RT1) × RM + (E / RT2) × RS) / 2 = (E / 2) × ((RM / RT1) + (RS / RT2)) However, the term (RM + RS) cannot be obtained, and the output voltage VO is not proportional to the combination of the detection resistances of the respective resistive sensors. Fuel remaining cannot be obtained.

Accordingly, in the present invention, in order to improve the accuracy of the combined output, the output voltage VO includes the combined value of the detection resistors (RM + RS) as a proportional term, and obtains a more accurate output voltage proportional to the remaining fuel amount. The purpose is to:

[0009]

A vehicle fuel detecting device according to the present invention is a fuel detecting device for detecting a fuel amount by a liquid level sensor installed in a fuel tank of a vehicle. Comprising first and second resistive sensors having movable contacts located at different locations in the tank,
The resistors of the first and second resistive sensors are connected in parallel to a power supply, and each movable contact is connected to an output resistor larger than the resistance value of each resistor, and each output terminal is connected to an output terminal. An adjustment resistor is connected in series with the resistor having a smaller resistance value among the resistors.

Further, according to the present invention, the resistance value of the output resistor is expressed by:
It is characterized by being the same.

Further, according to the present invention, the first and second resistive sensors may include a resistor having a resistive layer provided on a number of conductor electrodes formed in parallel along a movable contact sliding locus on an insulating substrate. An output conductor provided in parallel with the resistor, an output resistor provided in series with the output conductor on the output side, and a contact with the conductor electrode and the output electrode in conjunction with a float floating according to the amount of fuel. And a movable contact that slides, and an adjusting resistor is connected in series with one resistor of the resistive sensor.

Further, according to the present invention, the adjusting resistor RX is formed as a continuous resistor such that the resistors RT1 and RT2 of the first and second resistive sensors 1 and 2 have the same resistance value. It is characterized by having done.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS There are provided two resistive sensors 1 and 2 having movable contacts 1S and 2S arranged at different positions in a fuel tank of a vehicle. 2 resistors RT and RT2 are connected in parallel,
The output voltage corresponding to the detected resistance value RM based on the contact position of the movable contact 1S on the resistor RT1 of the one resistive sensor 1 is V1, and the detection resistance based on the contact position of the movable contact 2S on the resistor RT2 of the other resistive sensor 2 is detected. An output voltage corresponding to the value RS is obtained as V2, and an output resistor r having a large resistance value is connected to the output of each of the movable contacts 1S and 2S to combine the outputs, and the output is connected. The output voltage VO proportional to the remaining fuel amount is obtained. Then, an adjustment resistor RX is connected in series with at least one of the resistors.

With such a configuration, the combination of detection resistors (R
(M + RS), it is possible to obtain an accurate detection output voltage VO, and it is possible to make the detection of the remaining fuel amount using two resistance sensors more accurate.

[0015]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, in which a first resistive sensor 1 is provided at two different positions in a vehicle fuel tank as two resistive sensors as liquid level sensors. And a second resistance type sensor 2 are provided. These resistance type sensors 1 and 2 have movable contacts 1S and 2S which rotate in connection with a float arm floating on the liquid surface in the fuel tank. Resistive sensor 2 with adjustable resistance
For example, as shown in FIG. 2, a resistor RT2 formed by forming a number of conductor electrodes D in parallel on a ceramic insulating substrate P and printing a resistive material thereon is provided, and an output of the resistor RT2 is provided. The adjustment resistor RX is connected in series on the side.

In the structure of FIG. 2, the resistor RT2
An output conductor F is formed in parallel with the output conductor F, an output resistor r is connected to the output side of the output conductor F, and the other is grounded. The conductor electrode D of the resistor RT2 and the output conductor F are connected by a movable contact 2S, and the detection voltage V2 at the detection resistor RS determined by the contact position of the movable contact 2S on the resistor RT2 is applied to the output resistor from the movable contact 2S. r.

As the circuit connection, the resistors RT1 and RT2 of the respective resistive sensors 1 and 2 are connected in parallel to the vehicle-mounted power supply E, and the movable contact 1S of the resistor RT1 of the first resistive sensor 1 is contacted. The output voltage corresponding to the detected resistance value RM according to the position is determined as V1, and the output voltage corresponding to the detected resistance value RS according to the contact position of the movable contact 2S in the resistor RT2 of the other resistive sensor 2 is determined as V2. To combine the outputs, each movable contact 1
By connecting an output resistor r having a large resistance value to the outputs of S and 2S and connecting the output, an output voltage VO proportional to the remaining fuel amount is obtained. Then, an adjustment resistor RX is connected in series with the second resistor RT1. This adjustment resistor RX is composed of first and second resistors RT1 and RT2.
Is adjusted to a value satisfying RT1 = RT2 + RX.

Therefore, the output voltage VO is given by: VO = (V1 + V2) / 2 = ((E / RT1) × RM + (E / (RT2 + RX)) × RS) / 2 = ((E / RT1) × RM + (E / RT1) × RS) / 2 = (E / 2) × ((RM + RS) / RT2), and eventually the output voltage VO is output as a value proportional to (RM + RS). It becomes proportional and data corresponding to an accurate remaining fuel amount can be obtained. In the above-described embodiment, the adjustment resistor RX is formed independently in series with the second resistor RT2. However, the resistance value of the second resistor RT2 includes RX and, consequently, the first resistor RT1. It may be formed as a continuous resistor so as to be equal to. That is, the resistance value of the resistor RT1 in FIG. 2 is adjusted in advance so as to be equal to the resistance value of the resistor RT1 of the other resistance sensor 1 and printed on the conductor electrode D, or What is necessary is just to print continuously with a resistor. In this case, the resistance value can be easily adjusted by printing or trimming the resistor, and the manufacture of the resistance sensor can be further simplified.

The output voltage VO detected above is output as a value proportional to the combined resistance (RM + RS) of the detection resistances RM and RS in the two resistance sensors 1 and 2 as described above. The voltage VO is A / D-converted and digitally processed by a processing circuit such as a microcomputer to drive the indicating instrument, or easily and accurately by directing the output voltage VO to direct the indication with a voltmeter. It is possible to indicate the remaining fuel amount.

[0020]

The fuel detecting device according to the present invention comprises first and second resistive sensors having movable contacts arranged at different positions in a tank. Connect the resistors in parallel with the power supply, connect an output resistance greater than the resistance of each resistor to each movable contact, connect each output end to the output terminal, and make the resistance of each resistive sensor equal. By connecting the adjustment resistor in series with the smaller one of the resistance values of the resistors,
The combined output voltage is output as a value proportional to the detection resistance detected by each resistance sensor, and is proportional to the combination of the detection resistances of each resistance sensor to obtain an output corresponding to an accurate remaining fuel amount. be able to.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of a vehicle fuel detection device according to the present invention.

FIG. 2 is a structural explanatory view of a resistance type sensor of the vehicle fuel detection device according to the present invention.

FIG. 3 is a circuit configuration diagram showing a comparative example for explaining the fuel detection device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st resistance type sensor 2 2nd resistance type sensor RT1 1st resistor RT2 2nd resistor 1S 1st movable contact 2S 2nd movable contact RM Detection resistance RS Detection resistance r Output resistance RX Adjustment resistance E power supply

Claims (4)

[Claims] 1. A fuel detecting device for detecting a fuel amount by a liquid level sensor installed in a fuel tank of a vehicle, wherein the liquid level sensor has movable contacts arranged at different positions in the tank. First and second resistive sensors 1,
2, the resistors RT1 and RT2 of the first and second resistive sensors 1 and 2 are connected in parallel to a power supply, and each movable contact 1S, 2S has an output larger than the resistance of each resistor RT1, RT2. A resistor r is connected to connect each output terminal to an output terminal, and an adjusting resistor RX is connected in series with a resistor having a smaller resistance value among the resistors RT1 and RT2, thereby forming one resistor. A fuel detection device for a vehicle, wherein the combined resistance value of the other resistor having the smaller resistance value and the adjustment resistor RX is made equal. 2. The vehicle fuel detecting device according to claim 1, wherein the resistance values of the output resistors r are the same. 3. The first and second resistive sensors 1 and 2.
Is a resistor RT having a resistance layer provided on a number of conductor electrodes formed in parallel along a movable contact sliding locus on an insulating substrate P.
1, RT2, an output conductor provided in parallel along the resistors RT1 and RT2, an output resistor r provided on the output side in series with the output conductor, and a float floating according to the fuel amount. 2. The movable contact 1 </ b> S, 2 </ b> S that slides in contact with the conductor electrode and the output electrode, and an adjusting resistor RX is connected in series with one resistor of the resistive sensor. 3. Vehicle fuel detector. 4. The first and second resistive sensors 1 and 2.
So that the resistance values of the resistors RT1 and RT2 are equal.
The fuel detecting device for a vehicle according to claim 3, wherein the adjusting resistor (RX) is configured as a resistor formed continuously.