JPH0334654Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention is a low-liquid system that can accurately and reliably detect liquid levels in tanks installed on ships or offshore structures, especially low liquid levels. This relates to a position detection device.

[Prior Art] Conventional liquid level gauges used on ships and the like include a float type, an electromagnetic float type, a radio wave type, an air purge type, and a pressure receiving type.

In the float type, as shown in Figures 3 and 4, lashing fittings d and e are attached to the sounding stand b installed on the tank top a and the tank bottom c, respectively.
Two guide wires f, f are strung in the vertical direction via the lashing fittings d, e, and a float g is attached so as to be movable up and down along the guide wires f, f. One end of the unwound measuring tape i is connected, and the liquid level depth r in the tank j is measured by replacing the vertical movement of the float g with the unwinding length of the measuring tape i.

The electromagnetic float type is a float with a built-in permanent magnet q along a guide pipe p with a large number of built-in reed switches n, as shown in Figures 5 and 6.
g ₁ is attached so that it can be raised and lowered, and when float g ₁ goes up and down, the reed switch n that is close to the permanent magnet q
emits an electric signal m to remotely display the liquid level r.

The radio wave type transmits a radio wave t from a dedicated transmitter s installed at the top of the tank to the liquid level k, as shown in Figure 7.
The liquid surface depth r is measured by firing the liquid toward the liquid surface k and measuring the reflection time from the liquid surface k.

In the air purge type, as shown in FIG. 8, an air purge unit u is placed at the top a of the tank, and the lowest pressure at which the hub w can be discharged from the lower end of the air purge pipe v into the inside of the tank stored liquid is measured.

In the pressure receiving type, pressure gauges x ₁ , x ₃ , and x ₂ are placed at high, low, and intermediate positions in tank j, respectively, as shown in Figure 9, and the liquid level depth r is determined by the following formula. .

r = Index of pressure gauge x ₃ x Mounting height of pressure gauge x ₂ / Index of pressure gauge x ₃ - Index of pressure gauge x ₂ [Problem to be solved by the invention] While liquid level gauges are used, in order to prevent marine pollution, crude oil tankers are now required to clean their crude oil tanks during loading and unloading based on IMO regulations, and the ability to accurately detect low liquid levels has become important. It's starting to be done. However, each of the liquid level gauges described above has the following problems, and it has been desired to develop a new detection device. In other words, in the float type, when the float g moves downward, it comes into contact with the lashing fitting e at the bottom, so it is impossible to measure a liquid level lower than the liquid level at this time. Tape i is easy to break, and when cleaning a crude oil tank, the float g will be damaged if it is hit by water from the cleaning machine, so the float g must be rolled up.

With the electromagnetic float type, the height y of float _g1 is large, so the lowest measurable liquid level cannot be reduced.
There is a limit to the installation interval of reed switches n, making it impossible to improve the accuracy of indication.

Radio wave systems generally have unstable accuracy, and erroneous indications often occur, especially near the bottom of the tank.
In order to prevent diffused reflection, it is necessary to secure a radio wave reflecting surface (not shown) at the bottom of the crude oil tank, which imposes restrictions on the installation location.

The air purge type generally has poor accuracy, especially low liquid level detection accuracy.

The pressure-receiving type is fundamentally unsuitable for detecting low liquid levels.

[Means for solving the problem] The present invention was made to solve the above-mentioned problem, and includes an electric angle transmitter inside a box made of a non-magnetic material with a liquid honey structure fixed to the bottom of the liquid tank. A fixed shaft extending substantially horizontally is fixed to the side wall of the box, and a hollow shaft having a float and a counterweight on the outside is rotatably fitted to the outside of the fixed shaft. one end of a drive shaft for rotationally driving the angle transmitter is rotatably fitted into the inside of the box of the fixed shaft, and the fixed A pair of magnets are attached via arms extending perpendicularly to the axis so as to face each other across the side walls of the box body.

[Operation] Since the float is rotatably supported on a horizontal fixed shaft, it operates faithfully in response to fluctuations in the liquid level. Therefore, low liquid levels can be detected with high accuracy. Also,
Since the rotational movement of the float is transmitted to the electric angle transmitter by the magnetic force of the magnet, changes in the liquid level can be electrically detected and displayed remotely.

[Example] Hereinafter, an example of the present invention will be described based on the drawings. Figures 1 and 2 show an embodiment of the present invention, and the main parts of the device are a storage box 2 made of non-magnetic material (for example, stainless steel) fixed to the tank bottom 1, and a storage box 2 made of non-magnetic material (for example, stainless steel). 2, an intrinsically safe potentiometer 3 disposed within the storage box 2; a rotary float portion 7 rotatably supported on the outside portion 6 of a fixed shaft 5 that penetrates the side wall 4 of the storage box 2 in a substantially horizontal direction; It consists of an interlocking part 9 rotatably supported on the box inner part 8 of 5. Intrinsically safe type refers to a structural standard that allows for safe use in an explosive atmosphere without causing external sparks.

The storage box 2 has a liquid-tight structure and is formed in a vertical cylindrical or box shape, and supports an intrinsically safe potentiometer 3 on a bracket 10. Connected to the onboard monitoring panel.

The rotating float part 7 is constructed by a hollow shaft 12 that fits around the outer periphery of the fixed shaft box outer part 6, and an arm 13a extending perpendicularly to the fixed shaft 5 on the side of the hollow shaft 12 near the storage box 2. Magnet 1 attached
3. Float 1 installed on the far side from storage box 2
4 and a counterweight 15.

The interlocking part 9 includes a drive shaft 16 whose one end is externally fitted into the horizontal shaft box inner part 8 and whose other end is connected to the rotating part 18 of the intrinsically safe potentiometer 3, and the drive shaft 16 is connected to the inner wall of the storage box 2. the magnet 13 on the side closer to
The magnet 1 is attached via an arm 17a extending perpendicularly to the fixed shaft 5 at a position opposite to the fixed shaft 5.
It consists of 7 etc.

Next, the operation of this device will be explained. Since the storage box 2 is made of non-magnetic material, the magnets 13,
17 are magnetically coupled by magnetic flux penetrating the side wall of the storage box 2. Now, when the liquid level k falls from the position shown by the solid line to the position shown by the imaginary line, the float 14 also rotates to the position shown by the imaginary line (arrow l),
The movement of the float 14 is transmitted to the drive shaft 16 via the magnets 13 and 17, changing the electrical resistance of the intrinsically safe potentiometer 3, and the intrinsically safe potentiometer 3 is proportional to the rotation angle θ of the float 14. A voltage is output, and this voltage signal m is displayed remotely on an indicator (not shown).

It should be noted that the present invention is not limited to the above-described embodiments, and it goes without saying that various changes can be made without departing from the gist of the present invention.

[Effects of the invention] As described above, the present invention exhibits the following excellent effects.

(i) Since the float rotates freely around a fixed axis, it can faithfully respond to fluctuations in liquid level and detect low liquid levels with high accuracy.

(ii) Since the float movement is detected as a voltage change, this voltage change can be guided to a desired position inside the ship via a conductor and displayed remotely.

(iii) The structure is strong because it does not use conventional measuring tapes, guide wires, or other parts that are susceptible to hull vibration.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the present invention,
Fig. 1 is a partially cutaway side view, Fig. 2 is a view taken from the - direction in Fig. 1, Figs. 3 to 9 are explanatory diagrams of conventional liquid level gauges, and Fig. 3 is a float type. 4 is an enlarged view of the part in FIG. 3, and FIG. 5 is a partially cutaway side view of the electromagnetic float type.
FIG. 6 is an enlarged cutaway view of the part shown in FIG. 5, FIG. 7 is a cutaway side view of the radio wave type, and FIGS. 8 and 9 are side views of the air purge type and pressure receiving type, respectively. In the figure, 1 is the tank bottom, 2 is a storage box, 3 is an intrinsically safe potentiometer, 5 is a fixed shaft, 7 is a rotating float part, 9 is an interlocking part, 13 and 17 are magnets, 1
3a and 17a are arms, 14 is a float, 15 is a counterweight, and 16 is a drive shaft.

Claims (1)

[Scope of utility model registration request] An electric angle transmitter is disposed in a box made of a non-magnetic material with a liquid structure fixed to the bottom of the liquid tank, and a fixed shaft extending substantially horizontally is fixed to the side wall of the box, passing through the box of the fixed shaft. A hollow shaft having a float and a counterweight on the outside is rotatably fitted on the outer part, and one end of a drive shaft for rotationally driving the angle transmitter is rotatably fitted on the inside of the box of the fixed shaft. A pair of magnets were attached to the outside of the hollow shaft and the drive shaft at positions close to the side walls of the box body through arms extending perpendicularly to the fixed shaft so as to face each other across the side wall of the box body. A low liquid level detection device characterized by: