JPH073357B2 - Liquid level indicator - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid level gauge suitable for measuring the liquid level of a liquid such as a solvent contained in a container, and more particularly to a liquid level gauge in the fields of food industry and semiconductor industry. As described above, the present invention relates to a liquid level gauge suitable for application in a field in which contamination of liquid is disliked.

[0002]

2. Description of the Related Art FIG. 7 shows a Japanese Patent Application No.
It is a diagram which shows the use condition of the liquid level gauge by the technique described in the specification etc. of 30911. This level gauge is arm 1
The float 2 and the angle sensor 3 are attached to both ends of the arm 1. The angle sensor 3 is attached to a liquid level gauge main body 4 fixed to a support member (not shown). Further, the output signal of the angle sensor 3 is the multi-core cable 5
Through a signal processing circuit (not shown).

In the liquid level gauge constructed as shown in FIG. 7, the float 2 moves around the rotation axis of the angle sensor 3 in response to the rise or fall of the liquid level 8 of the liquid 7 contained in the container 6. And rotate in the direction of arrow P.

In this case, the movement amount H of the liquid surface 8 in the vertical direction Q (hereinafter referred to as liquid surface height as necessary) H is the length from the rotation axis of the angle sensor 3 to the center of the float 2 (generally, Is the length of the arm), and the rotation angle of the arm 1 is θ.

[0005]

[Equation 1] H = L · sin θ

Since the angle θ is obtained from the angle sensor 3, the signal processing circuit calculates the equation 1 and the liquid level height H
You can know.

As described above, the above-mentioned conventional liquid level gauge can also measure the liquid level height.

[0008]

By the way, in the conventional level gauge as shown in FIG. 7, the angle sensor 3, the level gauge main body 4 and, in some cases, the multicore cable 5 are in the liquid 7. It is submerged in and used.

However, when the angle sensor 3 and the liquid level gauge body 4 are submerged in the liquid 7 for use as described above, various inconveniences as described below may occur. . (1) It takes a lot of time to clean when the level gauge body 4, the angle sensor 3 and the like are contaminated. (2) The liquid level gauge body 4 and the like may stain the liquid 7. (3) When the liquid 7 is a solution of strong acid, alkali, etc., or a solvent of acetone, etc., the level gauge main body 4 etc. must be made of a material that can withstand these solutions and solvents, However, there is a problem that the manufacturing cost increases. (4) When the temperature of the liquid 7 is high, for example, even when measuring the liquid level height of hot coffee, there is a problem that the liquid level gauge main body 4 must be made of a material that can withstand the temperature.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a liquid level gauge in which a sensor can be arranged outside a container containing a liquid.

[0011]

As shown in FIGS. 1 and 6 , for example, a liquid level gauge of the present invention includes a float 11 for detecting a liquid level 23 of a liquid 22 contained in a container 21, and a float 11 for detecting the liquid level 23. 11 is attached to one end and the other end is rotated around the rotation axis G, and the arm 13 is connected to the other end of the arm 13 and is arranged outside the container 21 that outputs a signal according to the rotation of the arm 13. In the liquid level gauge including the sensor 15, the arm 13 is formed to have the non-linear portion 25, and the non-linear portion 25 straddles the edge 31 of the container 21.
Position and the horizontal position of the center of rotation G and the liquid level
It is arranged so that the reference position 23 is on the same horizontal position.

[0012]

According to the liquid level gauge of the present invention, since the arm 13 integrally formed with the float 11 has the non-linear portion 25, the non-linear portion 25 is used to make the arm 13 serve as a container. It becomes possible to straddle the edge 31. Therefore, the sensor 15 connected to the other end of the arm 13 can be arranged outside the container 21. Also, the horizontal position about the rotation axis G
And the reference position of the liquid surface 23 should be on the same horizontal position.
Since it is located in the
Can be secured.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the liquid level gauge of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of the entire apparatus to which the liquid level gauge according to this embodiment is applied.

The liquid level gauge according to this embodiment basically comprises a float 11, an arm 13 having one end attached to the float 11 and the other end attached to a holder 12, and an angle sensor 15 integrated with the holder 12. And a liquid level gauge body 16 to be formed.

The float 11 is for detecting the liquid level 23 of the liquid 22 contained in the container 21, and the float 11 is a holder as the liquid level 23 moves in the direction of arrow Q (vertical direction). It rotates in the arrow F direction through the arm 13 about the 12 axis (the rotation axis G of the angle sensor 15).

As can be seen from FIG. 1, the arm 13 is formed in a shape having a curved non-linear portion 25 and is a molded product of a glass tube. In addition, the float 11
It is made of hollow glass balls. The arm 13 and the float 11 are made of liquid-resistant glass, for example, quartz glass, so that the liquid 21 can be used even if the liquid 21 is a strong acid / alkali solution or a solvent such as acetone. It is possible to measure the liquid level height without being attacked.

Since the arm 13 is formed so as to be curved, the arm 13 can straddle the edge 31 of the container 21, so that the angle sensor 15 connected to the other end of the arm 13 is attached to the container 21. It can be located outside.

The other end of the arm 13 can be removed from the holder 12 with a screw 33.
When removed, the arm 13 and the float 11 can be easily washed. Since the angle sensor 15 and the liquid level gauge main body 16 that houses the angle sensor 15 are arranged outside the container 21, the liquid 22 does not become contaminated. Therefore, it is not necessary to use a material that is particularly resistant to solvents and the like. Even if it becomes dirty, the liquid 22
Since it is not dipped in, it is easy to wipe off the dirt.

The liquid level gauge main body 16 is supported by a support tube 17, and the support tube 17 is supported by a stand 18. The stand 18 and the container 21 are arranged on a base 32.

In this case, the axis of the holder 12, that is,
The height of the rotation axis G of the arm 13 from the base 32 and the liquid level 23
That the reference position (the position of the liquid surface 23 shown in FIG. 1) has the same height, the linearity of the output of the angle sensor 15 with respect to the rotation angle of the arm 13 integrated with the float 11. It is desirable to secure.

By making the support tube 17 expandable and contractible for use, it is easy to make the height of the rotating shaft G and the height of the reference position the same. Also, stand 1
As it comes with 8, it is also convenient to carry.

From the stand 18, a liquid level signal formed based on the output signal of the angle sensor 15 is output to an external display or the like through the multi-core shield wire 19.

FIG. 2 is a partial sectional side view showing a part of the liquid level gauge including the configuration of the angle sensor 15. FIG. 3 is a partial cross-sectional front view showing a part of the liquid level gauge including the configuration of the angle sensor 15. In FIG. 3, the liquid level gauge main body 16 is omitted.

2 and 3, the liquid level gauge main body 16
A cylindrical support 40 having a closed bottom is fixed to
A saturable coil 41, which is one member of the angle sensor 15, is fixed in the support 40. The material of the support 40 is a non-magnetic material such as SUS-304 or brass.

FIG. 4 shows the structure of the saturable coil 41. The saturable coil 41 is made of a thin permalloy core 4
2 having windings 46 and 46 wound around the core 44
Two saturable coils 41A and 41B are provided. The output of the saturable coil 41 is supplied to a detection circuit described later.

In FIGS. 2 and 3, a cylindrical case 47, which constitutes the holder 12 and covers the support 40, is closed coaxially with the support 40 by a support mechanism (not shown). In addition, it is arranged so that it can rotate in the direction of arrow F.

Magnets 48 and 49 arranged so that the N pole and the S pole face each other are fixed to the inner peripheral surface of the case 47. The magnets 48 and 49 together with the saturable coil 41 form the angle sensor 15.

With such a structure, a DC magnetic field acting on the saturable coil 41 is generated by the magnets 48 and 49. The case 47 and the magnets 48 and 49 form a magnetic field generating member. The case 47 is preferably made of a magnetic material.
It need not be a magnetic material.

The other end of the arm 13 is attached to the holder 12 with a screw 33. By loosening the screw 33 as described above, the arm 13 can be easily removed from the holder 12.

As shown in FIG. 1, when the liquid level 23 of the liquid 22 changes, the float 11 moves in the direction of arrow F due to the change of the liquid level 23. This movement is a movement about the axis 45 (see FIG. 2) of the holder 12, that is, the rotation axis G as the center of rotation as described above. Therefore, when the float 11 moves, the arm 13 moves, and the case 47 formed integrally with the holder 12 rotates in the arrow F direction (see FIGS. 1 and 3).

In accordance with this movement, the intersecting angle between the magnetic lines of force generated by the magnets 48 and 49 and the saturable coil 41 changes according to the angle of rotation. Then, the inductances of the saturable coils 41A and 41B change. This change in inductance is supplied to the detection circuit.

FIG. 5 is a circuit diagram showing the structure of the detection circuit 62.

In FIG. 5, saturable coils 41A, 41
The output terminal of B is connected to the detection circuit 62. This detection circuit 62 has a cycle of about 40 μs, a pulse width of about 1 μs,
It has a pulsed voltage oscillator 64 with a voltage amplitude of 30V, and the output of this oscillator 64 is supplied to the common connection point of the saturable coil 41 through one end of the secondary coil 65c of the transformer 65. The outputs of the saturable coil 41A and the saturable coil 41B are the one ends of the series resistors 66, 66 and the diode 6 respectively.
It is connected to the anode terminals of 7, 67.

The other ends of the series resistors 66, 66 are connected to the transformer 6
5 is connected to the other end of the secondary coil 65c. The cathode terminals of the diodes 67, 67 have output resistors 68, 68.
The output resistors 68, 68 and the other ends of the capacitors 69, 69 connected in parallel are connected to the other end of the secondary coil 65c. Also,
A capacitor 70 is connected between the cathode terminals of the diodes 67, 67, and both ends of the capacitor 70 are output terminals 81, 81. This output terminal 81,
An analog voltage output is generated across 81.

The process of generating the analog voltage output will be described in detail. The saturable coils 41A and 41B are
A pulsed current supplied from the oscillator 64 through the transformer 65 causes the magnetic saturation in opposite directions. When a DC magnetic field is applied to the core 44 in this state, one saturable coil (for example, the saturable coil 41
The inductance of A) increases and the inductance of the other saturable coil (thus, saturable coil 41B) changes so as to decrease. The pulse-shaped voltage supplied to the anode side of the diodes 67, 67 changes according to the change of the inductance, and accordingly the output resistance 68,
The rectified voltage generated at 68 also changes. Since the changes in the rectified voltage occur in the opposite directions, the output terminals 81, 81
The difference between these two rectified voltages appearing in between is the detection circuit 62.
Will be output. The difference in the rectified voltage becomes a sinusoidal voltage corresponding to the rotation angle of the saturable coil 41. Detection circuit 6
The voltage output of 2 is supplied to a signal processing device (not shown),
The signal processing device converts it into numerical data representing the liquid level. The converted numerical data is the multi-core shielded wire 19
(See FIG. 1) and is displayed, for example, on a display device or the like.

FIG. 6 shows the liquid level height (mm) and the detection circuit 62.
It is the figure which plotted the measurement example with the output (V) of. In this measurement example, the length of the arm 13 along the bend is 370 mm, and the angle sensor 15 and the float 11
The linear distance between them is 210 mm. In this example, it is possible to measure the liquid surface height from the reference position (position where the height of the angle sensor 15 and the liquid surface height match = 0 mm) to +100 mm and −160 mm, and in that range, practically sufficient. It has linearity. The rotation angle is 8 for the liquid level.
It was −22 degrees at 0 mm and +44 degrees at −140 mm.

As described above, according to the above-described embodiment, the arm 13 integrally formed with the float 11 has the non-linear portion 2
Have five. Therefore, the non-linear portion 25 can be used to allow the arm 13 to straddle the edge 31 of the container 21, and the angle sensor 15 connected to the other end of the arm 13 can be arranged outside the container. You can

Therefore, with such a configuration and operation, it is possible to solve the problems described in the section of the prior art. That is, even if dirt is attached to the liquid level gauge main body 16, the angle sensor 15, etc., the liquid 22 is not contaminated, and even if it is dirty, cleaning is easy. Furthermore, the liquid 22 is a strong acid.
Even if a solution such as an alkali or a solvent such as acetone is used, the liquid level gauge main body 16 side does not need to be made of a material that can withstand those solutions and solvents, and the manufacturing cost does not increase. Moreover, when the temperature of the liquid 22 is high, for example, when measuring the liquid level height of hot coffee, it is not necessary to make the liquid level gauge main body 16 from a material that can withstand the temperature.

As described above, the arm 13 and the float 11 are made of quartz glass or the like, so that the liquid surface is excellent in liquid resistance and can be appropriately used in the fields of food industry and semiconductor industry. The total is obtained. In this case, since the arm 13 and the float 11 can be removed, cleaning is easy.

Further, the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various configurations can be adopted without departing from the gist of the present invention.

[0041]

As described above, according to the liquid level indicator of the present invention, the arm integrally formed with the float has a non-linear portion. Will be able to straddle the edge of the container. Therefore, there is an effect that the sensor connected to the other end of the arm can be arranged outside the container. Also, center of rotation axis
The horizontal position of and the reference position of the liquid surface are on the same horizontal position.
Since it is arranged like this, the linearity of the sensor output
The effect of being able to secure is also obtained.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing a usage state of a liquid level gauge according to an embodiment of the present invention.

2 is a partial cross-sectional side view showing the configuration of an angle sensor and the like in the liquid level gauge shown in FIG.

3 is a partial cross-sectional front view showing the configuration of an angle sensor and the like in the liquid level gauge shown in FIG.

FIG. 4 is a front view showing a configuration of a saturable coil that constitutes an angle sensor.

5 is a circuit diagram of a detection circuit connected to the saturable coil shown in FIG.

FIG. 6 is a diagram showing an actually measured value of the relationship between the liquid level and the output voltage measured by the liquid level gauge shown in FIG.

FIG. 7 is a partial cross-sectional view showing a usage state of a conventional liquid level gauge.

[Explanation of symbols]

 11 Float 13 Arm 15 Angle Sensor 21 Container 22 Liquid 25 Non-linear Section

Claims (1)

[Claims] 1. A float for detecting a liquid level of a liquid contained in a container, the float having one end attached thereto and the other end attached thereto.
In a liquid level gauge including an arm that rotates about a rotation axis and a sensor that is connected to the other end of the arm and that outputs a signal according to the rotation of the arm, the sensor is provided outside the container. A shape having a non-linear portion, and the non-linear portion is arranged so as to straddle the edge of the container.
And the horizontal position of the center of rotation and the reference position of the liquid surface
A liquid level gauge characterized in that and are arranged on the same horizontal position .