JPH10122938A - Liquid level measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measuring device requiring no complicated maintenance work or inspecting work by connecting a float instructing bar to a float floated on a liquid, and detecting a distortion generated in the float instructing bar by the buoyancy stress received by the float. SOLUTION: The upper end of a float 13 floated in water 12 injected into a vessel 11 is connected to the end part of a float instructing bar 14 by a fixed part 15. The fixed part 15 is pushed up by the action of the buoyancy stress of the float 13. At that time, since the other end part of the float instructing bar 14 is fixed to the wall part of the vessel 11 by a fixed part 16, a fine displacement or distortion corresponding to the buoyancy stress is caused in the float instructing bar 14 when the fixed part 15 is pushed up. This distortion is detected by a strain gauge 17 mounted on the lower surface of the float instructing bar 14, and transmitted to a distortion observing device 19 through a lead wire 18. The distortion observing device 19 measures the level of the water 12, or the depth D from the magnitude of the detected distortion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid level measuring device for measuring a liquid level of a liquid stored in a container or the like.

[0002]

2. Description of the Related Art A conventional liquid level measuring apparatus will be described with reference to FIG. 3 by taking a case where a liquid contained in a container is, for example, water. Reference numeral 31 denotes a container, and water 3 is contained in the container 31.
2 are stored. Further, a liquid level measuring device 33 is provided integrally with the container 31. In the liquid level measuring device 33,
A float 331 for measuring the water level is provided. The float 331 floats on the water surface S, and moves up and down according to the rise and fall of the water level. Further, a displacement rod 332 is connected to the float 331,
Is connected to a gear 333. Gear 333 is another
A pointer 335 for indicating a water level is connected to the gear 334. Then, the pointer 335
A scale 336 for reading the position is provided. Reference numeral 337 denotes a limit switch, which is provided on a path on which the pointer 335 moves.

In the above-described configuration, for example, when the water level rises, the float 331 rises, and the displacement rod 332 rotates counterclockwise in the figure. When the displacement rod 332 rotates, the gear 33
3 rotates, and further, a gear 334 connected to the gear 333.
Rotates. Then, the pointer 33 fixed to the gear 334
5 indicates a direction corresponding to the rotation of the gear 334.

In this case, the indication of the pointer 335 corresponds to the water level. Therefore, the indication of the pointer 335 is changed to the scale 33.
The water level can be measured by reading at 6. When the water level rises above a certain value, the pointer 335 contacts the limit switch 337 to operate the limit switch 337. Thereby, for example, a signal that warns the rise of the water level is output,
Alternatively, the supply of water to the container 31 is stopped.

[0005]

In the conventional liquid level measuring device, a mechanical connection is used for transmitting motion such as rotation of the gears 334 and 335. In the case of such a structure, a mechanical connection such as between the gears 334 and 335
It is necessary not to hinder the displacement. For this reason, complicated maintenance work and inspection work such as supplying lubricating oil to a mechanical connection part are required. Further, when a limit switch 337 that operates in contact with the pointer 335 is incorporated therein, a problem such as chattering occurs.

An object of the present invention is to solve the above-mentioned drawbacks and to provide a liquid level measuring apparatus which does not require complicated maintenance work and inspection work.

[0007]

According to the liquid level measuring device of the present invention, a float whose lower part is located in a liquid contained in a container and whose upper part is located on the surface of the liquid is fixed partially, The float is connected to a freely movable portion, and a float indicator rod on which a buoyancy stress applied to the float acts on the connected portion, and attached to the float indicator rod,
A strain gauge for measuring a strain generated in the float indicator rod.

According to the above-described configuration, the strain generated on the float indicator rod is measured by the strain meter to measure the liquid level of the liquid. Therefore, a mechanical connection such as a gear is not used unlike the conventional liquid level measuring device. For this reason,
Complicated maintenance work and inspection work such as supplying lubricating oil to a mechanical connection part are not required. In addition, since there is no mechanical connection, it is resistant to mechanical vibration. In addition, since the liquid level can be taken out as an electric signal, a limit switch or the like is not required even when the liquid level rises or falls, and mechanical chattering of the switches can be eliminated.

[0009]

FIG. 1 shows an embodiment of the present invention.
This will be described with reference to FIG.

Reference numeral 11 denotes a container in which water 12 is stored. The float 13 is floating in the water 12. The float 13 is formed of a columnar uniform rigid body, and the lower half is submerged in water and the upper half floats on the water surface S. The upper end of the float 13 is the float indicator rod 1
4 is connected to the end portion by a fixing portion 15. The other end of the float indicator rod 14 is firmly fixed to the wall of the container 11 and the fixing portion 16. A strain gauge 17 is attached to the lower surface of the float indicator rod 14. Strain gauge 1
7 is configured to detect, for example, a strain generated in the float indicator rod 14 by using expansion and contraction of a metal resistor. The strain gauge 17 is connected to a strain observation device 19 through a lead wire 18.

Next, a method for measuring the water level with the liquid level measuring apparatus having the above-described configuration will be described. The float 1 is attached to the fixed portion 15 to which the float 13 and the float indicator rod 14 are connected.
A buoyancy stress Ff of 3 acts. The buoyancy stress Ff acts to push up the fixing portion 15 between the float 13 and the float indicating rod 14. At this time, since the other end of the float indicating rod 14 is fixed to the wall of the container 11 by the fixing part 16, the float indicating rod 14 has a small displacement (δr) corresponding to the buoyancy stress Ff according to Young's law. ), So-called distortion occurs. Then, the strain of the float indicator rod 14 is detected by the strain gauge 17 and sent to the strain observation device 19 through the lead wire 18.

In this case, the strain generated on the float indicator rod 14 corresponds to the buoyancy stress Ff acting on the fixing portion 15 of the float indicator rod 14, and thus the position of the float 13. Therefore, the liquid level, that is, the depth D is measured based on the magnitude of the strain detected by the strain gauge 17. The magnitude of the strain detected by the strain gauge 17 is taken out by the strain observation device 19 as liquid level data. Then, in the strain observation device 19, based on the detected liquid level data, for example, various warnings for the rise or fall of the liquid level are issued, or
A control signal for controlling the supply and stop of the liquid is output.

Here, a description will be given of a pattern of distortion generated in the float indicating rod with reference to FIG. In FIG. 2, parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted. Reference numeral 14 denotes a float indicating rod, on which a float buoyancy stress Ff acts. As a result, the float indicating rod 14 is distorted, and a small displacement (δr) is generated from the dotted line state 14a to the solid line state 14b. This displacement (δr) is detected by the strain gauge 17 as described with reference to FIG.

In the above embodiment, the strain gauge 1
7, a metal resistance wire strain gauge using a metal resistance wire is used. However, as the strain gauge 17, a semiconductor strain gauge utilizing the piezoresistive effect or the float indicator rod 14 is used.
It is also possible to use an optical strain meter or the like that detects the distortion of the optical axis as a change in the optical axis.

Although the above embodiment has been described with reference to the case where the water level is measured, the present invention can be applied to the measurement of the liquid level of a liquid other than water.

[0016]

According to the present invention, a liquid level measuring apparatus which does not require complicated maintenance work and inspection work can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram illustrating an embodiment of the present invention.

FIG. 3 is a schematic configuration diagram illustrating a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Container 12 ... Water 13 ... Float 14 ... Float indicator stick 15 ... Fixed part 16 ... Fixed part 17 ... Strain gauge 18 ... Lead wire 19 ... Strain observation device

Claims (1)

[Claims] 1. A float whose lower part is located in a liquid stored in a container and whose upper part is located on the surface of the liquid, and the float is connected to a part which is fixed and freely movable, and is connected to the float. A liquid level measuring device comprising: a float indicator rod on which a buoyancy stress applied to the float acts, and a strain gauge attached to the float indicator rod and measuring a strain generated in the float indicator rod.