JP2000205933A - Level detecting and indicating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a level detecting and indicating apparatus which when a container is full of liquid, can surely indicate that it is full and which, when the container is almost empty, can surely indicate that it is empty. SOLUTION: This level detecting and indicating apparatus includes a level detector 1 in which a contact member 15 is slidably placed on a resistor 16 having a sliding contact surface and in which a float disposed within a container of liquid is associated with the contact member 15, so that by causing the contact member 15 to slide over the resistor 16 as the float rises and falls, the level detector 1 outputs a detection signal indicating a resistance value matching the level of the liquid, and a level indicator which calculates an indication of the level according to the detection signal of the level detector 1 and displays the indication. An infinite resistance area 18 wherein electrical resistance is almost infinite is provided on the part of the liquid detector 1 where the contact member 15 is located when almost no liquid is in the container. The liquid detector 1 also has an indication means which causes the level indicator to provide an indication of a less-than-empty condition when a detection signal from the level detector 1 indicates an infinite resistance value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid level detection display device suitable for a fuel gauge for a vehicle and the like.

[0002]

2. Description of the Related Art Conventionally, a resistance type liquid level detector having a float is known as a liquid level detector of a device for detecting a fuel level in a fuel tank of an automobile and displaying the level on a fuel gauge. I have. This resistance type liquid level detector is configured such that a resistor having a sliding contact surface is formed on a substrate, a contact member is slidably disposed on the resistor, and a float is provided via a float arm. The contact member is connected to the portion, and the contact member slides on the resistor according to the vertical movement of the float.

Then, the liquid level detection display device applies a weak current to the resistor, detects the voltage between one end of the resistor and the contact member, and sets the voltage as a liquid level detection value. The liquid level is displayed on a liquid level indicator such as a meter based on the measured value. Also, in this type of liquid level detection display device, when the resistance value (voltage value) of the resistance type liquid level detector increases to a predetermined value, the empty (empty) and the resistance value (voltage value) decrease to the predetermined value. In many cases, full (full) is displayed. Conversely, when the resistance value (voltage value) increases to a predetermined value, full (full), and when the resistance value (voltage value) decreases to a predetermined value, the empty (empty) value becomes empty. ) Is displayed.

[0004]

In recent years, in some cases, poor fuel and various additives have been added to automotive fuels, and these influences have caused the sliding contact of the resistor of the liquid level detector. It is possible that foreign matter is generated between the surface and the contact member. When foreign matter is generated between the sliding contact surface of the resistor and the contact member, the resistance value (voltage value) tends to increase abnormally, and when the resistance value is small on the full side and large on the empty side, the state becomes full. Regardless, due to the increase in the resistance value, the display of the fuel gauge does not indicate the full state. In the opposite case, the resistance value is high on the full side and low on the empty side.
If foreign matter enters between the resistor and the contact member in the empty state,
Where the minimum resistance value (voltage value) is normally detected,
A large resistance value (voltage value) was detected, and the indication of the fuel level was not less than empty, and the indication could be made as if the fuel had entered the fuel tank to some extent.

[0005] The present invention has been made in view of the above points, and when the liquid in the container is full, the full display is made, and when the liquid is almost empty, the display of less than the empty is made surely. It is an object of the present invention to provide a liquid level detection display device capable of performing the above.

[0006]

In order to achieve the above object, a liquid level detecting and displaying device according to the present invention comprises a contact member slidably provided on a resistor having a sliding contact surface, and a liquid container. Liquid level detection that outputs a detection signal indicating a resistance value corresponding to the liquid level by linking a float arranged inside the contact member to the contact member and sliding the contact member on a resistor according to the vertical movement of the float And a liquid level indicator for calculating a display value of the liquid level based on the detection signal of the liquid level detector and displaying the display value. When the liquid in the container is substantially empty, an infinite resistance area is provided at the position where the contact member is located to make the electric resistance almost infinite, and the detection signal from the liquid level detector is an infinite resistance value. Display means for making the display value of the liquid level indicator less than empty when indicating And it features.

According to a second aspect of the present invention, in the liquid level detection display device, the liquid level detector increases the resistance value between one end of the resistor and the contact member as the liquid level in the container rises. The resistance value decreases as the liquid level decreases, and when the resistance value increases to a predetermined value, a detection signal of fullness is output, and when the resistance value decreases to a predetermined value, an empty detection signal is output. And

[0008]

According to the liquid level detection display device having the above-described structure, the float of the liquid level detector disposed in the container moves up and down according to the liquid level position, and the contact member accordingly resists. The display means slides on the body, and the resistance value between one end of the resistor and the contact member changes according to the sliding position of the contact member, and the resistance value is displayed as a detection signal (voltage signal or the like) indicating the liquid level position. Is output to The display means calculates a display value of the liquid level based on the detection signal from the liquid level detector, and displays the display value on the liquid level display.

When the liquid level in the container is at the lowest position and is almost empty, the contact member of the liquid level detector enters the infinite resistance region, so that the resistance between the resistor and the contact member is substantially infinite. And the detection signal at this time indicates that the resistance value is substantially infinite. Therefore, when the detection signal from the liquid level detector indicates an infinite resistance value, the display means controls the display value to be less than empty, and the liquid level indicator displays less than empty.

As described above, when the liquid level in the container drops to a substantially empty position, the contact member of the liquid level detector enters an infinite resistance region where the electric resistance is substantially infinite.
The detected value corresponding to the substantially infinite resistance value is reliably input to the display means. The display means, when a detection signal corresponding to the infinite resistance value is input, forcibly determines the display value so that the display value is less than the empty value. Even if foreign matter is generated between members, the liquid level indicator can reliably display less than empty. On the full side, if the resistance value increases, the display will be on the full side, and the full display can be performed reliably when the battery is full.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration diagram of a liquid level detection display device for detecting and displaying the remaining fuel amount of a fuel tank of an automobile. The liquid level detection display device takes in a liquid level detector 1 disposed in the fuel tank 2 and a detection signal sent from the liquid level detector 1 and displays a detection level indicated by the signal on the liquid level display 3. And a display control device 5 for performing the operation.

Liquid level detector 1 arranged in fuel tank 2
As shown in FIGS. 1 and 2, a float 12 with a float arm 13 floating on the fuel level and a rotatable contact plate 14 fixed to a shaft on which the base of the float arm 13 is supported. And a resistor (resistance layer) 16 formed on the substrate 17 by printing or the like, and the contact plate 1
And a contact member 15 fixed to the tip of the contact member 4 and slidably in contact with the resistor 16. A constant voltage power supply is connected to both ends of the resistor 16, and a resistance value that changes with the rotation of the contact member 15 is extracted as a voltage value between the contact member 15 and one end of the resistor 16, and a detection signal thereof is output. Is output.

That is, when the float 12 moves up and down in accordance with the fuel level, the liquid level detector 1
Contact member 15 slides on the resistor 16, the resistance value between one end of the resistor 16 and the contact member 15 changes according to the fuel level, and outputs this as a voltage signal. Further, as shown in FIG. 2, the resistor 16 is formed in a substantially sector shape, and its end on the empty side, that is, the fuel liquid level in the fuel tank 2 drops to the level of almost empty, and the float 12 is moved to the inside of the tank. When the contact member 15 at the tip of the contact plate is lowered to the lowermost position, the contact member 15 comes off the end of the resistor 16 and comes into contact with the non-conductive substrate. The contact member 15 is a resistor 16
When contact is made with a portion that is farther away, the resistance value between one end of the resistor 16 and the contact member 15 becomes substantially infinite, and this portion constitutes the infinite resistance region 18.

The display control device 5 includes a CPU 6, a ROM 7,
The microcomputer 6 is mainly composed of a microcomputer having an input / output circuit 9 and the like, and the CPU 6 executes sampling and display processing of detection data as described later based on program data stored in the ROM 7 in advance. The RAM 8 of the memory that can be written and read at any time temporarily stores the sampled value, the average value thereof, and the like. The input / output circuit 9 includes an A / D converter, an interface, etc., converts a detection signal sent from the liquid level detector 1 into a digital signal and inputs the digital signal, and outputs display data to the display driver 4. .

The driver 4 is connected to the liquid level indicator 3 and controls the driving of the liquid level indicator 3 to display the liquid level. As the liquid level indicator 3, a liquid crystal segment type indicator or the like can be used in addition to a cross coil type instrument having a pointer 3a as shown in FIG. For example, when using a cross-coil type instrument and driving it by DC, the driver 4
An A / A converter and an amplifier are provided, a sine wave signal and a cosine wave signal are generated in accordance with the sent digital signal, and both signals are output to two cross coils to drive the hands. When a liquid crystal segment type display is used, the driver 4 is configured to drive and display the segment indicated by the input display data.

Next, the operation of the liquid level detection display device will be described with reference to the flowchart of FIG. When the key switch of the vehicle is on, the liquid level detector 1 in the fuel tank always outputs a detection signal indicating the liquid level to the input / output circuit 9 of the display control device 5 both when stopping and when traveling. Is done.

First, at step 100, the CPU 6 samples the detection data, takes in the detection signal indicating the liquid level sent from the liquid level detector 1, and stores it.
This sampling is performed, for example, every 100 ms.
For example, 30 sampling data, that is, the detected values are stored in the RAM 8 for 3 seconds.

Next, in step 110, the average value of the detected liquid level detected during the predetermined time is calculated. By averaging a plurality of sampling values in this way, large fluctuations in instantaneous detected values due to fluctuations in the liquid level are smoothed, and unnecessary fluctuations in the displayed values are prevented. Next, in step 120, it is determined from the calculated average value whether the resistance value between the resistor 16 and the contact member 15 of the liquid level detector 1 has become substantially infinite. That is, as shown in FIG. 2, the resistor 16 and the contact member 15 are in contact with each other from the time when the fuel liquid level in the fuel tank 2 is full to just before the empty state, and the resistance value therebetween is within a predetermined range. , In which case it is determined to be non-infinite.

On the other hand, when the fuel liquid level in the fuel tank 2 is at the lowest position and is almost empty (empty), the contact member 15 of the liquid level detector 1 comes off the resistor 16 and the infinite resistance area 18 Therefore, the resistance value between the resistor 16 and the contact member 15 becomes substantially infinite, and the voltage value of the detection signal at this time becomes a high voltage indicating the same, and the resistance value becomes substantially infinite from the detected value. Judge that there is.

If it is determined that the resistance value of the liquid level detector 1 is non-infinite, the routine proceeds to step 140, where a display value (the deflection angle of the pointer 3a of the cross-coil meter) is calculated from the average of the detected values. On the other hand, if it is determined that the resistance value of the liquid level detector 1 is substantially infinite, the process proceeds to step 130, where the display value is less than the empty level of the liquid level display 3, that is, the deflection angle of the pointer is changed as shown in FIG. It is determined to be below the minimum empty position. Then, the display value data calculated and determined as described above is output from the input / output circuit 9 to the driver 4 in step 150, and the driver 4 controls the drive of the liquid level display 3, and the display value is displayed on the liquid level display. It is displayed on the display 3.

As described above, when the liquid level of the fuel tank 2 drops to a substantially empty position, the contact member 15 of the liquid level detector 1 separates from the resistor 16 and the nonconductive substrate 17.
At this time, the detected value of the voltage corresponding to the substantially infinite resistance value is input to the display control device 5 because the display control device 5 comes into contact with the infinite resistance region 18 provided above. When the display control device 5 receives the detection signal corresponding to the infinite resistance value, the display control device 5 forcibly determines the display value so as to make the display value less than the empty value. 1
No foreign matter enters between the gaps 5 and the liquid level indicator 3 can reliably display a value less than empty. Further, since the resistance value can be made sufficiently large on the full side, if the resistance value increases, the display will be on the full side, and the full display can be reliably performed when the tank is full.

In the above embodiment, as the liquid level in the tank rises, the resistance value (voltage value) of the liquid level detector increases,
The lower the liquid level in the tank, the lower the resistance (voltage value) of the liquid level detector. Conversely, the higher the liquid level in the tank, the lower the resistance value (voltage) of the liquid level detector. Value)
The resistance value (voltage value) of the liquid level detector may be configured to increase as the liquid level in the tank decreases. In this case, an infinite resistance region where the electric resistance is substantially infinite is provided at the position where the contact member is located when the tank is full.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a liquid level detection display device according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of the liquid level detector 1.

FIG. 3 is a front view of the liquid level indicator 3.

FIG. 4 is a flowchart illustrating a display process.

FIG. 5 is a graph showing a relationship between a resistance value of a liquid level detector with respect to a liquid level and a display value of a liquid level indicator.

[Explanation of symbols]

 1-Liquid level detector 2-Fuel tank 3-Liquid level indicator 5-Display control device 6-CPU 7-ROM 8-RAM 15-Contact member 16-Resistor 18-Infinite resistance area

Claims (2)

[Claims] A contact member is slidably disposed on a resistor having a sliding contact surface, a float disposed in a liquid container is linked to the contact member, and the float is moved in accordance with the vertical movement of the float. A liquid level detector that outputs a detection signal indicating a resistance value according to a liquid level by sliding the contact member on the resistor, and a liquid level level based on the detection signal of the liquid level detector. A liquid level display device that calculates a display value and displays the display value; anda liquid level detection display device comprising: when the liquid in the container is substantially empty,
An infinite resistance region where the electrical resistance is substantially infinite is provided at a position where the contact member is located, and when a detection signal from the liquid level detector indicates an infinite resistance value, the display value of the liquid level indicator is displayed. A liquid level detection display device comprising a display means for determining that the liquid level is less than empty. 2. The liquid level detector, wherein as the liquid level in the container rises, the resistance value between one end of the resistor and the contact member increases, and as the liquid level falls, the resistance value decreases. The liquid level detection display device according to claim 1, wherein when the resistance value increases to a predetermined value, a full detection signal is output, and when the resistance value decreases to a predetermined value, an empty detection signal is output. .