JPH0894413A - Liquid level measuring device - Google Patents

Abstract

PURPOSE: To obtain a liquid level measuring device operable irrespective of the conductivity of an object, which enhances an ignition-resistant property by a method wherein a permanent magnet and a magnetic sensor are used and the liquid level is detected in a noncontact manner and without a contact via magnetism. CONSTITUTION: A turning arm which is coupled to a float 2 floating on a liquid surface is turned by using a shaft 11 as an axis. A magnetoresistance element 13 for a magnetic sensor is arranged coaxially, and so as to be faced, with the shaft composed of a permanent magnet 12 buried in, and installed at, the rear end part of the arm, and an operational amplifier 14 and a meter are connected electrically to the element 13. The magnet 12 is turned together with the arm at the same angle and in the same direction, it is partitioned by a sidewall 4b for an enclosure part, and it is insulated electrically from the element 13. That is to say, the element 13 is partitioned by the sidewall 4b for a liquid level measuring device 10, and it can be arranged and installed at the outside of a liquid storage tank, and it is especially favorable for a liquid storage body which is conductive and strongly flammable. By using the device 10 which is formed in a noncontact manner and without a contact in this manner, an increase or a decrease in the storage amount of the liquid storage body and a liquid level are displayed on the meter by means of the magnet 12 and the element 13.

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 the liquid level of various liquids stored in a water tank, a gasoline tank or other general liquid storage layers.

[0002]

2. Description of the Related Art Conventionally, a liquid level measuring apparatus for measuring a liquid level in a liquid storage tank such as a gas tank is shown in FIGS.
As shown in FIG. 2, the tip of the rotating arm 3 is connected to the float 2 floating on the liquid surface of the liquid storage 1, and the rear end of the rotating arm 3 is rotatably supported by the frame portion 4 of the measuring device. Has been done.

A conductive contact piece 5 formed integrally with the rear end of the turning arm 3 and arranged at a predetermined angle and turning coaxially with the turning arm 3, A variable resistor 6 arranged so as to always be in sliding contact with the contact piece 5 and having an electric resistance value which varies according to a deviation of a contact position with the contact piece 5; a meter 7 electrically connected to the variable resistor 6; And a power supply unit 8 for supplying power to the liquid level measuring device 9.

According to the liquid level measuring device 9, when the amount of water stored in the stored liquid 1 changes, the height of the float 2 changes and the rotating arm 3 and the contact piece 5 rotate at an angle.

When the contact piece 5 rotates, the position of contact with the variable resistor 6 moves up and down in FIG. 1 and the resistance value of the variable resistor 6 changes, so that the current value changes and the needle of the meter 7 changes. Fluctuates according to the strength of the magnetic field due to the current value, and the level of the liquid level can be determined.

[0006]

Since the liquid level measuring device 9 uses the variable resistor 6, it is necessary to always supply electricity to the frame unit 4.
Cannot be used when is electrically conductive, for example, water. Further, since the contact with the contact piece 5 is made mechanically, there is a possibility that contact failure may occur. As described above, the conventional liquid level measuring device has a problem to be solved in that it cannot be used for a conductive storage liquid and that the contact operation of the contact piece is reliable.

The present invention has been made in view of the above-mentioned problems, and is not only capable of being measured regardless of the presence or absence of conductivity, but also having further improved ignition resistance as compared with conventional ones. It is an object of the present invention to provide a liquid surface level measuring device in which a meter surely follows the surface level.

[0008]

The object of the present invention to solve the above problems and to achieve the above objects is to provide a permanent magnet that is rotated by vertical movement of a float floating on a liquid surface, and a rotation of the permanent magnet. A liquid level measuring device comprising at least a magnetic sensor whose electric resistance value changes and a meter electrically connected to the magnetic sensor.

The magnetic sensor is a magnetically sensitive element and is electrically insulated from the permanent magnet;
Further, an amplifying means is interposed between the magnetic sensor and the meter.

[0010]

According to the liquid level measuring device of the present invention, the level change of the liquid level is grasped as the angle change by the permanent magnet and the magnetic sensor electrically insulated from the permanent magnet and reflected on the meter. Even small changes in the liquid level can be detected accurately, and since there is no electrical contact and it is insulated, it can be used as a level meter even for conductive liquid storage, and there is no risk of sparks scattering and there is a risk of ignition. Not at all.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, one embodiment according to the present invention will be described in detail with reference to the drawings. It should be noted that the portions corresponding to the conventional example will be described with the same reference numerals.

The liquid level measuring device 10 according to the present invention comprises:
As shown in FIG. 1 to FIG. 3, for example, a float 2 floating on the liquid surface of a stored liquid 1 such as water or gasoline, a rotating arm 3 having a tip end connected to the float 2, and a rotating arm 3 A rotary shaft 11 which is integrally formed at the rear end and rotatably supports it, a frame portion 4a which locks the rotary shaft 11, and a rear end of the rotary arm 3 which is coaxial with the rotary shaft 11. A permanent magnet 12 whose one side surface is exposed and buried, and a magnetoresistive element 1 as a magnetically sensitive element which is arranged so as to face the rotation axis of the permanent magnet 12 coaxially.
3, an operational amplifier 14 electrically connected to the magnetoresistive element 13, a meter 7 electrically connected to the operational amplifier 14, and a power supply 8.

The permanent magnet 12 is adapted to rotate in the same direction at the same angle together with the rotating arm 3 made of metal or synthetic resin. 4b and are electrically insulated. That is, as shown in FIG. 2, the magnetoresistive element 13 is provided on the side wall 4b of the frame 4 in the liquid level measuring device 10.
In other words, it can be disposed outside the liquid storage tank instead of inside the liquid storage tank containing the liquid storage 1. This is an important advantage for conductive and flammable stored liquids.

Next, the magnetoresistive element 13 as the magnetically sensitive element will be described with reference to FIGS. 4 to 6.
As shown in FIG. 5, between the permanent magnet 12 and the magnetoresistive element 13 which is disposed close to and opposed to the permanent magnet 12,
Is rotated in a certain direction, the direction of the magnetic flux H of the permanent magnet 12 changes, and the resistance value of each of the resistance elements RA, RB,... Constituting the Wheatstone bridge circuit changes.

That is, as shown in FIGS. 4A and 4B,
When the magnetic flux H rotates by the angle θ in the direction of the arrow, the resistance of the resistance elements RA and RC decreases and the resistance of the resistance elements RB and RD increases.

This changes the current value, which is amplified by the operational amplifier 14 and the needle of the meter 7 is swung. As shown in FIG. 6, from the relationship between the rotation angle of the permanent magnet 12 from the reference position and the output voltage, a range having a linear characteristic curve, for example, a range of angles from −20 ° to + 20 °. Thus, the liquid level is measured with high accuracy. A Hall element may be used as the magnetically sensitive element.

With the liquid level measuring device 10 formed as described above, the storage amount of the stored liquid (eg, water, gasoline, heavy oil, light oil, kerosene, other petroleum products, etc.) 1 in the liquid storage tank can be increased or decreased and The liquid level is as shown on the meter 7 by the permanent magnet 12 and the magnetoresistive element 13.

In addition, the electric and electronic parts such as the magnetoresistive element 13 and the operational amplifier 14 are provided on the side walls 4 of the frame 4 made of an insulating material such as synthetic resin.
Since a non-contact / contactless structure is insulated by appropriately providing a gap by a, 4b, etc., there is no inconvenience such as poor contact due to repetitive operation of the contact piece as in the prior art, and sparks are scattered and ignited. Not only is there no danger at all, but even if the stored liquid is conductive water, it can be used as a level meter.

Therefore, the liquid level measuring device 10 of the present invention
Is optimal for measuring the liquid level in a liquid storage tank in which the storage liquid 1 is water, gasoline, or the like.

[0020]

As described above, in the liquid level measuring device according to the present invention, the permanent magnet which is rotated by the vertical movement of the float floating on the liquid surface and the electrical resistance value which is caused by the rotation of the permanent magnet. Since it has at least a changing magnetic sensor and a meter electrically connected to the magnetic sensor, it becomes possible to detect the liquid surface level via magnetism in a non-contact / non-contact manner, and a non-conductive Not only the stored liquid, but also the conductive stored liquid such as water can be used as a level meter, which has an excellent effect of expanding versatility.

Further, the magnetic sensor is a magnetically sensitive element and is electrically insulated from the permanent magnet; and further, an amplifying means is interposed between the magnetic sensor and the meter so that the magnetic sensor is electrically conductive. In addition to being a liquid level measuring device that is also suitable for liquid storage liquids that have a strong flammability, it is possible to have a structure in which a magnetic sensor or the like is provided not on the water storage side of a highly flammable liquid storage liquid but outside the liquid storage tank. This is an extremely safe measuring device that is less likely to catch fire than the liquid level measuring device, and further has the excellent effect that the change in the liquid level is accurately grasped by the amplifying means and becomes a highly accurate measuring device.

[Brief description of drawings]

FIG. 1 is an explanatory view of a usage state of a liquid level measuring device according to the present invention.

FIG. 2 is a sectional view of the liquid level measuring device.

FIG. 3 is a circuit configuration diagram of the liquid level measuring device.

FIG. 4 is a pattern layout view (a) of a magnetoresistive element of the liquid level measuring apparatus and an equivalent circuit diagram.

FIG. 5 is an explanatory diagram showing a relationship between a magnetoresistive element and a permanent magnet of the liquid level measuring device.

FIG. 6 is an output characteristic diagram showing the relationship between the rotation angle of the magnetic field of the magnetoresistive element of the liquid level measuring apparatus and the output voltage.

FIG. 7 is an explanatory diagram illustrating a use state of a liquid level measuring device according to a conventional example.

FIG. 8 is a circuit configuration diagram of a liquid level measuring device according to the conventional example.

[Explanation of symbols]

 Reference Signs List 1 liquid storage, 2 float, 3 rotating arm, 4 frame, 4a, 4b side wall, 7 meter, 8 power supply, 10 liquid level measuring device, 11 rotation axis, 12 permanent magnet, 13 magnetoresistive element, 14 operational amplifier .

Claims (3)

[Claims] 1. A permanent magnet which rotates by vertical movement of a float floating on a liquid surface, a magnetic sensor whose electric resistance value changes by the rotation of the permanent magnet, and a meter electrically connected to the magnetic sensor. And a liquid level measuring device comprising: 2. The magnetic sensor is a magnetically sensitive element,
The liquid level measuring device according to claim 1, wherein the liquid level measuring device is electrically insulated from the permanent magnet. 3. The amplifying means is interposed between the magnetic sensor and the meter.
The liquid level measuring device according to.