JP2664874B2 - Liquid level measurement device - 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 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 the figure, the tip of the turning arm 3 is connected to the float 2 floating on the liquid surface of the stored liquid 1, and the rear end of the turning arm 3 is rotatably supported on the frame 4 of the measuring device. Have been.

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. In addition, since the contact with the contact piece 5 is made mechanically, a 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.

[0007] The present invention has been made in view of the above problems, and not only can be measured regardless of the presence or absence of conductivity, the flammability is further improved than the conventional, An object of the present invention is to provide a liquid level measuring device in which a meter reliably follows a level according to a level.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems of the present invention and achieve the above-mentioned object, a gist of a permanent magnet which is rotated by a vertical movement of a float floating on a liquid surface, and which is electrically connected to the permanent magnet, is provided. A magnetoresistive element that is insulated and detects a rotation angle of a permanent magnet by changing its electric resistance value by its rotation, and the permanent magnet and the magnetoresistive element are made of synthetic resin.
While being stored in the inner space of the frame of the frame,
A liquid surface level measuring device comprising at least a frame part which is separated by a provided side wall and hermetically seals the magnetoresistive element, and a meter electrically connected to the magnetoresistive element.

[0009] An amplifying means is interposed between the magnetoresistive element 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 an angle change by the permanent magnet and the magnetoresistive element electrically insulated from the permanent magnet and reflected on the meter. In addition, small changes in the liquid level can be detected with high accuracy, and since there is no electrical contact and insulation is provided, it can be used as a level meter even for conductive stored liquids, and there is no danger of sparks igniting and igniting There is no. Also, by using a magnetoresistive element,
Since the liquid level can be detected by the rotation angle of the permanent magnet, and the liquid level is not detected by a change in the distance of the magnetic force, the level measuring device can be downsized as a whole. Further, since the permanent magnet and the magnetoresistive element are provided in an electrically insulated manner , the permanent magnet and the magnetoresistive element can be housed in the liquid storage tank, and other components can be arranged at high density around the liquid storage tank. I can do it.

[0011]

Next, an embodiment of the present invention will be described in detail with reference to the drawings. Parts corresponding to those of 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 FIGS. 1 to 3, for example, a float 2 floating on a liquid surface of a stored liquid 1 such as water or gasoline, a rotating arm 3 having a tip connected to the float 2, A rotary shaft 11 integrally formed at a rear end portion and rotatably supported; a side wall 4a of a frame body portion 4 for fixing the rotary shaft 11;
A frame portion 4 buried coaxially with 1 and exposing one side surface at the rear end of the rotating arm 3 and surrounded by the side walls 4a and 4b;
Permanent magnet 12 housed in the internal space of
In the opposed with the second rotation axis coaxial with specifications in the sidewall 4b
A magnetoresistive element 13 as a magnetically sensitive element cut and enclosed in a closed space, an operational amplifier 14 electrically connected to the magnetoresistive element 13, and a meter electrically connected to the operational amplifier 14 7 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 having the liquid storage 1. This is an important advantage for conductive and flammable stored liquids.

Next, the magnetoresistive element 13 as the magnetic sensitive element will be described with reference to FIGS.
As shown in FIG. 5, between the permanent magnet 12 and the magnetoresistive element 13 which is disposed in close proximity to the permanent magnet 12, as shown in FIG.
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.

As a result, the current value changes, and the current value 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. Further, 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 liquid (for example, water, gasoline, heavy oil, light oil, kerosene and other petroleum products) 1 in the storage tank is increased and decreased, and The liquid level is as indicated 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, the liquid level measuring apparatus according to the present invention comprises a permanent magnet which is rotated by the up and down movement of a float floating on the liquid surface, and which is electrically insulated from the permanent magnet and provided with the same. A magnetoresistive element for detecting a rotation angle of a permanent magnet by changing an electric resistance value by rotation, a frame body containing the permanent magnet and the magnetoresistive element, and electrically connected to the magnetoresistive element Since there is at least a meter that has been set, there is no danger of ignition because sparks do not scatter, and the use of a magnetoresistive element makes it possible to detect the liquid level with the rotation angle of the permanent magnet Since the liquid level is not detected by a change in distance of the magnetic force, an excellent effect that the level measuring device can be downsized as a whole can be obtained. In addition, the downsizing of the level measuring device allows the permanent magnet and the magnetoresistive element to be electrically insulated from each other so that they can be stored with high security inside the liquid storage tank. This makes it possible to arrange other components at high density around the device, and has an excellent effect of contributing to high-density mounting in a limited narrow space such as an automobile.

In addition, since the amplifying means is interposed between the magnetoresistive element and the meter, there is an excellent effect that a change in the liquid level is accurately grasped by the amplifying means and a high-precision measuring device is obtained. .

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a use 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 diagram (a) of a pattern arrangement of a magnetoresistive element of the liquid level measuring device 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 a relationship between a rotation angle of a magnetic field of a magnetoresistive element and an output voltage of the liquid level measuring device.

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 (2)

(57) [Claims] 1. A permanent magnet which is rotated by a vertical movement of a float floating on a liquid surface, and which is electrically insulated from the permanent magnet and changes an electric resistance value by the rotation to change the rotation angle of the permanent magnet. A magnetoresistive element to be detected ; and a frame body made of a synthetic resin insulator , wherein the permanent magnet and the magnetoresistive element are combined.
A side wall housed in the interior space and provided in the interior space
A liquid level measuring device, comprising at least a frame portion which is partitioned by the above and seals the magnetoresistive element, and a meter electrically connected to the magnetoresistive element. 2. The liquid level measuring device according to claim 1, wherein amplification means is interposed between the magnetoresistive element and the meter.