JP2000121410A - Device for detecting liquid level - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid level detecting device for precisely detecting a liquid level without opening the cover of a container. SOLUTION: An ultrasonic sensor 12 is butted through soft rubber 32 to a side face 20A of a container 20. The ultrasonic sensor 12 is supported by the top end of a shaft 26 of a gauge 14, and displaced to a vertical direction along the side face 20A according as the shaft 26 is displaced. When a power is supplied, an output wave is radiated from the ultrasonic sensor 12, and the reflected wave is detected. The output level of this reflected wave is compared with a reference level so that whether or not fluid is present until a measuring position can be detected. Then, the measuring position where this detected result is changed is judged as a liquid level. That is, the liquid level is detected by gradually displacing the shaft 26 from top to bottom, and an operator is informed by a buzzer 40. The position (height) of the ultrasonic sensor 12 is displayed at a display part 28 of the gauge 14 so that the height of battery liquid can be easily and precisely detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid level detector for detecting the liquid level of a liquid stored in a container from outside.

[0002]

2. Description of the Related Art In a container in which a liquid is stored, for example, a battery case of an automobile, it is important for maintenance to check the remaining amount of the battery liquid, in particular, the liquid level of the battery liquid. As described above, many liquid level detectors for detecting the liquid level of the liquid stored in the container have been conventionally developed. In these liquid level detecting devices, the liquid level is detected by opening the lid of the container and allowing the detection terminal to enter the liquid.

[0003]

However, it is troublesome to remove the lid of the container and insert the detection terminal every time the liquid level is checked. In addition, when the liquid stored in the container is a battery liquid or the like, the liquid contains dilute sulfuric acid, so that the liquid must be handled with care and the workability of detecting the liquid level is reduced.

There is also a method of checking the liquid level inside by making the container translucent. However, if the container is installed in a narrow space, it is difficult to check the liquid level from the side. There was an inconvenience.

The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a liquid level detecting device that accurately detects a liquid level without opening a lid of a container.

[0006]

According to the first aspect of the present invention, there is provided a liquid level detecting device for detecting a liquid level of a liquid from the outside with respect to a container storing the liquid therein. An ultrasonic sensor abutting on an outer side surface of the radiator, a displacement unit for displacing the ultrasonic sensor in a vertical direction along the side surface, and the ultrasonic sensor displaced by the displacer unit is emitted into the container. And a liquid level detecting means for detecting a liquid level based on a change in the output level of the reflected wave with respect to the ultrasonic wave.

The operation of the first aspect will be described.

The ultrasonic sensor is in contact with the outer side surface of the container, emits ultrasonic waves to the inside of the container, and detects reflected waves from the boundary surface between the inner side surface of the container and the liquid or gas. The output level of this reflected wave greatly differs depending on whether the boundary surface with the container is liquid or gas. Therefore, by displacing the ultrasonic sensor vertically along the outer side surface of the container by the displacing means, the state inside the container at the measurement position is changed from liquid to gas or from gas to liquid based on the change in the output level of the reflected wave. Can be detected. That is, the liquid level can be detected.

As described above, the liquid level can be accurately detected by displacing the ultrasonic sensor in the vertical direction along the outer side surface of the container. Therefore, simplification of the liquid level checking operation and improvement of the liquid level detection accuracy are achieved.

According to a second aspect of the present invention, in the first aspect of the present invention, the displacement means supports a mounting member mounted on an upper surface of the container, the ultrasonic sensor, and an outer side surface of the container. And a displacing member displaced along the axis.

By mounting the displacement means on the upper surface of the container by the mounting member, the ultrasonic sensor supported by the displacement member can be displaced along the outer side surface of the container. Therefore, even when the container is installed in a narrow space, it is possible to dispose the ultrasonic sensor on the side surface movably along the outer side surface. As a result, the liquid level of a container installed in a narrow space can also be detected with high accuracy.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A liquid level detecting device according to an embodiment of the present invention will be described in detail with reference to FIGS.

FIG. 1 shows a liquid level detecting device used for a battery container.

The liquid level detecting device 10 basically comprises an ultrasonic sensor 12, a gauge 14 as a displacement means, and a measuring unit 16 as a liquid level detecting means.

The gauge 14 has a mounting member 18 having an L-shaped cross section.
Is attached to the lid 22 of the battery case 20 via the. The gauge 14 includes a gauge body 24 and a gauge body 24.
And a shaft 26 which is displaceably inserted through the shaft 26. The gauge main body 24 has a display unit 28 that detects and displays the amount of displacement of the shaft 26.

The end of the shaft 26 has a spring 3
0, one end of the ultrasonic sensor 12 is supported.
The other end of the ultrasonic sensor 12 is in contact with the side wall 20A of the battery case 20 via the soft rubber 32. That is, the ultrasonic sensor 12 is in contact with the side wall 20 </ b> A of the container 20 via the soft rubber 32 by the elastic force of the spring 30. Therefore, by displacing the shaft 26 in the vertical direction, the ultrasonic sensor 12 (soft rubber 32) slides on the side wall 20A and is displaced in the vertical direction.

The measuring unit 16 connected to the ultrasonic sensor 12
Has a buzzer 40 and an ultrasonic sensor 1 inside.
2 has a detection unit 42 for detecting the liquid level based on the output signal from the control unit 2. As shown in FIG. 2, the detection unit 42 receives the output signal of the ultrasonic sensor 12 and outputs a drive signal to the buzzer 40, and compares the output signal with the output level of the reflected wave received by the ultrasonic sensor 12. ROM 46 for storing reference levels and the like, and RAM 4 for temporarily storing output signals and the like
8. CPU 50 for comparing the output level with the reference level;
And I / O 44, ROM 46, RAM 48, CPU 5
0 is provided for connecting the bus 52.

Incidentally, inside the battery case 20,
Battery fluid 54 is stored.

The operation of the liquid level detecting device 10 having such a configuration will be described.

First, an operator attaches the gauge 14 to the cover 22 of the battery case 20 via the attachment member 18.
As a result, the ultrasonic sensor 12 supported at the tip of the shaft 26 comes into contact with the side wall 20A of the container 20 via the soft rubber 32.

In this state, when the power supply (not shown) is turned on, the detection by the ultrasonic sensor 12 is started.

The ultrasonic sensor 12 emits a predetermined ultrasonic wave A (see FIGS. 4A and 4B) toward the inside of the container 20 so that the ultrasonic wave is transmitted to the inner surface of the side wall 20A of the container 20. Reflected wave B reflected at interface with liquid or gas
1, B2 can be received.

For example, referring to FIG.
Is measured at a position higher than the liquid level 56 (FIGS. 1 and 12).
A), the ultrasonic wave A is almost reflected at the boundary surface between the side wall 20A and the gas, and is detected as a reflected wave B1. On the other hand, when the ultrasonic sensor 12 measures at a position lower than the liquid surface 56 (see FIGS. 1 and 12B), the ultrasonic wave A is partially reflected at the boundary surface between the side wall 20A and the liquid and detected as a reflected wave B2. You.

As shown in FIG. 2, the output levels of the reflected waves B1 and B2 are larger when the boundary surface is a container and a gas than when the boundary surface is a container and a liquid. By setting a boundary value between them, that is, the reference level L0, it is possible to detect whether or not there is liquid inside the container up to the height of the measurement position.

The liquid level detecting method in the detecting section 42 will be described with reference to the flowchart shown in FIG.

First, when the power is turned on, k =
It is set to 1 (step 100).

Next, the shaft 26 is slowly displaced in a fixed direction (for example, from the upper end to the lower end of the side wall 20A).

The ultrasonic sensor 12 emits an ultrasonic wave A into the container at regular intervals to detect reflected waves B1 and B2 from the interface between the container and the liquid or gas. This reflected wave is input from the ultrasonic sensor 12 to the I / O 44 of the detection unit 42. The maximum output level Lk of the reflected wave is taken into the RAM 46 (step 102).

Reference level L preset in ROM 48
0 and the maximum output level Lk (step 10).
4). As described above, when the maximum output level Lk of the reflected wave is equal to or higher than the reference level L0, it is determined that there is no liquid in the container 20 up to the measurement position (height) of the ultrasonic sensor 12, and the maximum output level Lk of the reflected wave is determined. Is equal to or lower than the reference level L0, it is determined that there is liquid in the container 20 up to the measurement position of the ultrasonic sensor 12.

Therefore, when the maximum output level Lk is equal to or higher than the reference level L0, it is determined that there is no liquid in the container 20 at the measurement position Hk of the ultrasonic sensor 12, and Hk = 0.
(No liquid) is input to the RAM (step 106). On the other hand, when the maximum output level Lk is equal to or lower than the reference level L0, it is determined that there is liquid in the container 20 up to the measurement position Hk of the ultrasonic sensor 12, and Hk = 1 (liquid present) is input to the RAM ( Step 108).

Subsequently, it is determined whether or not reading of the maximum output level Lk of the reflected wave is the first time (k = 1) (step 110). This is because the liquid level is detected based on a comparison of two consecutive determination results, and therefore the determination cannot be made only by the first time.

Therefore, if it is determined in step 110 that this is the first time (k = 1), k is incremented (step 112), the maximum output level Lk + 1 is fetched in step 102, and the detection work is performed. repeat.

On the other hand, if it is determined in step 110 that it is not the first time (k ≠ 1), it is determined whether or not the previous determination result Hk-1 and the current determination result Hk are the same (step 110). 114). This is the previous judgment result Hk-1
If the determination result Hk is the same as the current determination result, it is determined that the ultrasonic sensor 12 is continuously displacing the portion with or without liquid inside the container. Therefore, it is determined that the ultrasonic sensor 12 has not yet reached the liquid level 56, k is incremented (step 112), and the detection operation from step 102 is repeated.

Conversely, if the previous and current determination results are not the same, it is assumed that the measurement position of the ultrasonic sensor 12 has entered the container 20 from the liquid-containing portion to the liquid-less portion or from the liquid-less portion to the liquid-containing portion. Is shown. That is, it is determined that the ultrasonic sensor 12 has reached the liquid level 56, and the buzzer 40 is driven to notify the worker that the liquid level 56 has been detected (step 116).

Therefore, the operator stops the displacement of the shaft 26 and checks the depth displayed on the display unit 28. If the liquid level is lower than a predetermined value, the battery liquid is refilled into the container.

As described above, in the liquid level detecting device 10 according to the present embodiment, the ultrasonic sensor 12 supported on the tip of the shaft 26 in the gauge 14 is displaced in the vertical direction along the side wall 20A of the container 20. Alone, the liquid level can be detected simply and accurately (detection accuracy is about ± 1 mm).

Therefore, it is not necessary to open the lid 22 of the battery case 20 to check the level of the battery liquid stored in the battery case 20. Further, there is no possibility that the battery liquid adheres to the operator in order to check the liquid level, and the workability is improved.

Further, since the measurement can be performed only by attaching the gauge 14 to the lid 22 of the battery case 20 and displacing the shaft 26, even a container installed in a narrow space, such as the battery case 20, is attached to the side wall 20A. It is possible to make measurement by bringing the ultrasonic sensor 12 into contact.

In this embodiment, the shaft 26 is manually displaced. However, the shaft 26 may be automatically displaced.

In this embodiment, the output level of the reflected wave is compared with the reference level. However, another example may be used as long as the liquid level is detected based on the change in the output level of the reflected wave. For example, a detection method may be adopted in which the liquid level is set when the amount of change in the acquired maximum output level exceeds a certain value.

[0041]

According to the first aspect of the present invention, the reflected wave of the ultrasonic wave emitted from the ultrasonic sensor which is vertically displaced along the outer side surface of the container by the displacement means is detected, and the output level of the reflected wave is detected. , The liquid level can be detected with high accuracy. Therefore, it is possible to easily and accurately detect the liquid level without opening the container.

According to the second aspect of the present invention, the ultrasonic sensor is moved up and down along the side surface by displacing the displacement member along the side surface of the container by mounting the displacement means on the upper surface of the container via the mounting member. Therefore, the ultrasonic sensor can be brought into contact with the side surface of the container installed in the narrow space, and the liquid level can be detected with high accuracy.

[Brief description of the drawings]

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

FIG. 2 is a block configuration diagram of a detection unit according to one embodiment of the present invention.

FIG. 3 is a flowchart showing a detection method of the liquid level detection device according to one embodiment of the present invention.

4A is a diagram showing a waveform of an ultrasonic wave emitted by an ultrasonic sensor and a waveform of a reflected wave received by the ultrasonic sensor and reflected from a boundary surface between a container and a gas, and FIG. 4B is a diagram showing an ultrasonic wave; It is a figure which shows the ultrasonic wave which a sensor emits, and the waveform of the reflected wave reflected from the boundary surface of the container and liquid which the ultrasonic sensor received.

[Explanation of symbols]

 Reference Signs List 10 Liquid level detector 12 Ultrasonic sensor 14 Gauge (displacement means) 16 Measurement unit (liquid level detection means)

Claims (2)

[Claims] 1. A liquid level detecting device for detecting a liquid level of a liquid from outside with respect to a container storing the liquid therein, comprising: an ultrasonic sensor abutting on an external side surface of the container; Displacement means for vertically displacing the ultrasonic sensor along the side surface, based on a change in the output level of a reflected wave with respect to the ultrasonic wave emitted into the container from the ultrasonic sensor displaced by the displacement means A liquid level detecting device, comprising: liquid level detecting means for detecting a liquid level. 2. The apparatus according to claim 1, wherein the displacing unit includes: a mounting member mounted on an upper surface of the container; and a displacing member that supports the ultrasonic sensor and displaces along an outer side surface of the container. The liquid level detection device according to claim 1.